MEMORY存储芯片MAX3490ECSA+T中文规格书

Half-Duplex RS-485-/RS-422-Compatible Transceiver with AutoDirection Control MAX13487E/MAX13488E General DescriptionThe MAX13487E/MAX13488E +5V, half-duplex, ±15kV ESD-protected RS-485/RS-422-compatible transceivers feature one driver and one receiver. The MAX13487E/MAX13488E include a hot-swap capability to eliminate false transitions on the bus during power-up or live insertion.The MAX13487E/MAX13488E feature Maxim’s propri-etary AutoDirection control. This architecture makes the devices ideal for applications, such as isolated RS-485 ports, where the driver input is used in conjunction with the driver-enable signal to drive the differential bus.The MAX13487E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free trans-mission up to 500kbps. The MAX13488E driver slew rate is not limited, allowing transmit speeds up to 16Mbps.The MAX13487E/MAX13488E feature a 1/4-unit load receiver input impedance, allowing up to 128 trans-ceivers on the bus. These devices are intended for half-duplex communications. All driver outputs are protected to ±15kV ESD using the Human Body Model. The MAX13487E/MAX13488E are available in an 8-pin SO package. The devices operate over the extended -40°C to +85°C temperature range.Applications Isolated RS-485 InterfacesUtility MetersIndustrial ControlsIndustrial Motor DrivesAutomated HVAC SystemsBenefits and Features •AutoDirection Saves Space and BOM Cost •AutoDirection Enables Driver Automatically on Transmission, Eliminating an Opto or Other Discrete Means of Isolation •8-Pin SO Package •Robust Protection Features for Telecom, Industrial,and Isolated Applications •Hot-Swap Capability to Eliminate False Transitions on the Bus During Power-Up or Live Insertion •Extended ESD Protection for RS-485 I/O Pins (±15kV Human Body Model)•Options Optimize Designs for Speed or Errorless Data Transmission •Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission (MAX13487E)•High-Speed Version (MAX13488E) Allows for Transmission Speeds Up to 16Mbps •1/4-Unit Load, Allowing Up to 128 Transceivers on the Bus Ordering Information/Selector Guide+Note:All devices operate over the -40°C to +85°C temperature range.Pin Configuration/Typical Application Circuit appear at end of data sheet.Functional Diagram 19-0740; Rev 1; 2/15找MEMORY 、二三极管上美光存储MAX13487E/MAX13488E Half-Duplex RS-485-/RS-422-Compatible Transceiver with AutoDirection Control Integrated | 7Typical Operating Characteristics (continued)(V CC = +5.0V, T A = +25°C, unless otherwise noted.)RECEIVER PROPAGATION vs. TEMPERATURE(MAX13488E)TEMPERATURE (°C)R E C E I VE R P R O P A G A T I O N (n s )603510-1510203040-4085DRIVER PROPAGATION (500kbps)(MAX13487E)M A X 13487E t o c 17DI 2V/div A-B5V/div400ns/div DRIVER PROPAGATION (16Mbps)(MAX13488E)DI 2V/div A-B 5V/div 10ns/div RECEIVER PROPAGATION (16Mbps)(MAX13488E)MA X 13487E t o c 19B 2V/div RO 2V/div A2V/div10ns/div DRIVING 16nF (19.2kbps)(MAX13487E)M A X 13487E t o c 20DI2V/divA-B 5V/div10μs/div DRIVING 16nF (19.2kbps)(MAX13488E)M A X 13487E t o c 21DI2V/div A-B5V/div 10μs/div DRIVING 16nF (750kbps)(MAX13488E)M A X 13487E t o c 22DI 2V/div A-B 5V/div400ns/div。

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at General DescriptionThe MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E are low-power transceivers forRS-485 and RS-422 communications in harsh environ-ments. Each driver output and receiver input is protectedagainst ±15kV electro-static discharge (ESD) shocks,without latchup. These parts contain one driver and onereceiver. The MAX483E, MAX487E, MAX488E, andMAX489E feature reduced slew-rate drivers that minimizeEMI and reduce reflections caused by improperly termi-nated cables, thus allowing error-free data transmissionup to 250kbps. The driver slew rates of the MAX481E,MAX485E, MAX490E, MAX491E, and MAX1487E are notlimited, allowing them to transmit up to 2.5Mbps.These transceivers draw as little as 120µA supply cur-rent when unloaded or when fully loaded with disableddrivers (see Selector Guide ). Additionally, the MAX481E,MAX483E, and MAX487E have a low-current shutdownmode in which they consume only 0.5µA. All parts oper-ate from a single +5V supply.Drivers are short-circuit current limited, and are protectedagainst excessive power dissipation by thermal shutdowncircuitry that places their outputs into a high-impedancestate. The receiver input has a fail-safe feature that guar-antees a logic-high output if the input is open circuit.The MAX487E and MAX1487E feature quarter-unit-loadreceiver input impedance, allowing up to 128 trans-ceivers on the bus. The MAX488E–MAX491E aredesigned for full-duplex communications, while theMAX481E, MAX483E, MAX485E, MAX487E, andMAX1487E are designed for half-duplex applications.For applications that are not ESD sensitive see the pin-and function-compatible MAX481, MAX483, MAX485,MAX487–MAX491, and MAX1487.ApplicationsLow-Power RS-485 TransceiversLow-Power RS-422 TransceiversLevel TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area Networks Next-Generation Device Features ♦For Fault-Tolerant Applications:MAX3430: ±80V Fault-Protected, Fail-Safe, 1/4-Unit Load, +3.3V, RS-485 Transceiver MAX3080–MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited, RS-485/RS-422Transceivers ♦For Space-Constrained Applications:MAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,Profibus, RS-485/RS-422 Transceivers MAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 Package MAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422True Fail-Safe Receivers MAX3030E–MAX3033E: ±15kV ESD-Protected,+3.3V, Quad RS-422 Transmitters ♦For Multiple Transceiver Applications:MAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,SOT23, RS-485/RS-422 Transmitters ♦For Fail-Safe Applications:MAX3440E–MAX3444E: ±15kV ESD-Protected,±60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers ♦For Low-Voltage Applications:MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited,True RS-485/RS-422 TransceiversOrdering InformationOrdering Information continued at end of data sheet.Selector Guide appears at end of data sheet .19-0410; Rev 4; 10/03找MEMORY 、二三极管上美光存储±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 TransceiversFigure 6. IEC1000-4-2 ESD Test ModelFigure 8. Driver DC Test LoadFigure 7. IEC1000-4-2 ESD Generator Current WaveformFigure 9. Receiver Timing Test Load Figure 4. Human Body ESD Test ModelFigure 5. Human Body Model Current Waveform MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E10 Integrated。

MAX660 CMOS Monolithic Voltage ConverterM A X 660CMOS Monolithic Voltage Converter ______________Detailed DescriptionThe MAX660 capacitive charge-pump circuit eitherinverts or doubles the input voltage (see TypicalOperating Circuits ). For highest performance, loweffective series resistance (ESR) capacitors should beused. See Capacitor Selection section for more details.When using the inverting mode with a supply voltageless than 3V, LV must be connected to G ND. Thisbypasses the internal regulator circuitry and providesbest performance in low-voltage applications. Whenusing the inverter mode with a supply voltage above3V, LV may be connected to GND or left open. The partis typically operated with LV grounded, but since LVmay be left open, the substitution of the MAX660 for theICL7660 is simplified. LV must be grounded when over-driving OSC (see Changing Oscillator Frequency sec-tion). Connect LV to OUT (for any supply voltage) whenusing the doubling mode.__________Applications InformationNegative Voltage ConverterThe most common application of the MAX660 is as acharge-pump voltage inverter. The operating circuituses only two external capacitors, C1 and C2 (seeTypical Operating Circuits ).Even though its output is not actively regulated, theMAX660 is very insensitive to load current changes. Atypical output source resistance of 6.5Ωmeans thatwith an input of +5V the output voltage is -5V underlight load, and decreases only to -4.35V with a load of100mA. Output source resistance vs. temperature andsupply voltage are shown in the T ypical OperatingCharacteristics graphs.Output ripple voltage is calculated by noting the outputcurrent supplied is solely from capacitor C2 during one-half of the charge-pump cycle. This introduces a peak-to-peak ripple of:V RIPPLE = I OUT +I OUT (ESR C2)2(f PUMP ) (C2)For a nominal f PUMP of 5kHz (one-half the nominal 10kHz oscillator frequency) and C2 = 150µF with an ESR of 0.2Ω, ripple is approximately 90mV with a 100mA load current. If C2 is raised to 390µF, the ripple drops to 45mV.Positive Voltage Doubler The MAX660 operates in the voltage-doubling mode as shown in the T ypical Operating Circuit.The no-load output is 2 x V IN .Other Switched-Capacitor Converters Please refer to Table 1, which shows Maxim’s charge-pump offerings.Changing Oscillator Frequency Four modes control the MAX660’s clock frequency, as listed below:FC OSC Oscillator Frequency Open Open 10kHz FC = V+Open 80kHz Open or External See Typical Operating FC = V+Capacitor Characteristics Open External External Clock Frequency Clock When FC and OSC are unconnected (open), the oscil-lator runs at 10kHz typically. When FC is connected to V+, the charge and discharge current at OSC changes from 1.0µA to 8.0µA, thus increasing the oscillatorTable 1. Single-Output Charge Pumps。

±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 TransceiversThe major difference between tests done using the Human Body Model and IEC1000-4-2 is higher peak current in IEC1000-4-2, because series resistance is lower in the IEC1000-4-2 model. Hence, the ESD with-stand voltage measured to IEC1000-4-2 is generally lower than that measured using the Human Body Model. Figure 7 shows the current waveform for the 8kV IEC1000-4-2 ESD contact-discharge test.The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized.Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resis-tance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. Of course, all pins require this protec-tion during manufacturing—not just inputs and outputs. Therefore,after PC board assembly,the Machine Model is less relevant to I/O ports.MAX487E/MAX1487E:128 Transceivers on the Bus The 48kΩ, 1/4-unit-load receiver input impedance of the MAX487E and MAX1487E allows up to 128 transceivers on a bus, compared to the 1-unit load (12kΩinput impedance) of standard RS-485 drivers (32 transceivers maximum). Any combination of MAX487E/MAX1487E and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481E, MAX483E, MAX485E, and MAX488E–MAX491E have standard 12kΩreceiver input impedance.MAX483E/MAX487E/MAX488E/MAX489E:Reduced EMI and Reflections The MAX483E and MAX487E–MAX489E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. F igure 16 shows the driver output waveform and its Fourier analy-sis of a 150kHz signal transmitted by a MAX481E, MAX485E, MAX490E, MAX491E, or MAX1487E. High-frequency harmonics with large amplitudes are evident.F igure 17 shows the same information displayed for a MAX483E, MAX487E, MAX488E, or MAX489E transmit-ting under the same conditions. F igure 17’s high-fre-quency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.Low-Power Shutdown Mode(MAX481E/MAX483E/MAX487E) A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled. In shutdown, the devices typically draw only 0.5µA of supply current.RE and DE may be driven simultaneously; the parts are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown.F or the MAX481E, MAX483E, and MAX487E, the t ZH and t ZL enable times assume the part was not in the low-power shutdown state (the MAX485E, MAX488E–MAX491E, and MAX1487E can not be shut down). The t ZH(SHDN)and t ZL(SHDN)enable times assume the parts were shut down (see Electrical Characteristics).Figure 16. Driver Output Waveform and FFT Plot of MAX485E/MAX490E/MAX491E/MAX1487E Transmitting a 150kHz SignalFigure 17. Driver Output Waveform and FFT Plot ofMAX483E/MAX487E–MAX489E Transmitting a 150kHz SignalMAX481E/MAX483E/MAX485E/ MAX487E–MAX491E/MAX1487E 12±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 TransceiversOrdering Information (continued)Selector GuideChip InformationTRANSISTOR COUNT: 295MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E。

Half-Duplex RS-485-/RS-422-Compatible Transceiver with AutoDirection Control MAX13487E/MAX13488E General DescriptionThe MAX13487E/MAX13488E +5V, half-duplex, ±15kV ESD-protected RS-485/RS-422-compatible transceivers feature one driver and one receiver. The MAX13487E/MAX13488E include a hot-swap capability to eliminate false transitions on the bus during power-up or live insertion.The MAX13487E/MAX13488E feature Maxim’s propri-etary AutoDirection control. This architecture makes the devices ideal for applications, such as isolated RS-485 ports, where the driver input is used in conjunction with the driver-enable signal to drive the differential bus.The MAX13487E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free trans-mission up to 500kbps. The MAX13488E driver slew rate is not limited, allowing transmit speeds up to 16Mbps.The MAX13487E/MAX13488E feature a 1/4-unit load receiver input impedance, allowing up to 128 trans-ceivers on the bus. These devices are intended for half-duplex communications. All driver outputs are protected to ±15kV ESD using the Human Body Model. The MAX13487E/MAX13488E are available in an 8-pin SO package. The devices operate over the extended -40°C to +85°C temperature range.Applications Isolated RS-485 InterfacesUtility MetersIndustrial ControlsIndustrial Motor DrivesAutomated HVAC SystemsBenefits and Features •AutoDirection Saves Space and BOM Cost •AutoDirection Enables Driver Automatically on Transmission, Eliminating an Opto or Other Discrete Means of Isolation •8-Pin SO Package •Robust Protection Features for Telecom, Industrial,and Isolated Applications •Hot-Swap Capability to Eliminate False Transitions on the Bus During Power-Up or Live Insertion •Extended ESD Protection for RS-485 I/O Pins (±15kV Human Body Model)•Options Optimize Designs for Speed or Errorless Data Transmission •Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission (MAX13487E)•High-Speed Version (MAX13488E) Allows for Transmission Speeds Up to 16Mbps •1/4-Unit Load, Allowing Up to 128 Transceivers on the Bus Ordering Information/Selector Guide+Note:All devices operate over the -40°C to +85°C temperature range.Pin Configuration/Typical Application Circuit appear at end of data sheet.Functional Diagram 19-0740; Rev 1; 2/15找MEMORY 、二三极管上美光存储MAX13487E/MAX13488E Half-Duplex RS-485-/RS-422-Compatible Transceiver with AutoDirection Control Integrated | 7Typical Operating Characteristics (continued)(V CC = +5.0V, T A = +25°C, unless otherwise noted.)RECEIVER PROPAGATION vs. TEMPERATURE(MAX13488E)TEMPERATURE (°C)R E C E I VE R P R O P A G A T I O N (n s )603510-1510203040-4085DRIVER PROPAGATION (500kbps)(MAX13487E)M A X 13487E t o c 17DI 2V/div A-B5V/div400ns/div DRIVER PROPAGATION (16Mbps)(MAX13488E)DI 2V/div A-B 5V/div 10ns/div RECEIVER PROPAGATION (16Mbps)(MAX13488E)MA X 13487E t o c 19B 2V/div RO 2V/div A2V/div10ns/div DRIVING 16nF (19.2kbps)(MAX13487E)M A X 13487E t o c 20DI2V/divA-B 5V/div10μs/div DRIVING 16nF (19.2kbps)(MAX13488E)M A X 13487E t o c 21DI2V/div A-B5V/div 10μs/div DRIVING 16nF (750kbps)(MAX13488E)M A X 13487E t o c 22DI 2V/div A-B 5V/div400ns/div。

MEMORY存储芯片MT40A1G8PM083EA中文规格书一、产品概述MT40A1G8PM083EA是一款高性能的MEMORY存储芯片，采用先进的生产工艺，具有低功耗、高速读写、大容量等特点。

本产品适用于各类电子设备，如计算机、服务器、嵌入式系统等，为用户提供稳定可靠的存储解决方案。

二、主要特性1. 存储容量：1GB（8GBIT x 128）2. 工作电压：1.2V / 1.5V / 1.8V（可调）3. 数据传输速率：最高可达2133Mbps4. 封装形式：BGA（Ball Grid Array）5. 工作温度范围：40°C至+95°C6. 低功耗设计，支持深度节能模式7. 兼容JEDEC标准，具备ECC错误校验功能三、产品参数1. 尺寸规格：12mm x 12mm x 1.2mm2. 引脚数量：244个3. 引脚间距：0.8mm4. 电源需求：VDDQ（1.2V / 1.5V / 1.8V），VDD（1.2V / 1.5V / 1.8V）5. 输入输出信号：DQ、DQS、DQS、DM、RESET、CKE、CS、ODT、RAS、CAS、WE6. 时序参数：根据不同工作频率，提供多种时序配置，以满足不同应用需求四、应用领域1. 服务器及数据中心2. 高性能计算3. 嵌入式系统4. 工业控制5. 消费类电子产品敬请关注后续内容，我们将为您提供更多关于MT40A1G8PM083EA 存储芯片的详细信息。

五、兼容性与接口1. 支持DDR4 SDRAM接口，兼容JEDEC DDR4规范。

2. 适用于单通道、双通道和四通道配置，可根据实际应用需求灵活选择。

3. 支持突发长度为8和16的读写操作，提高数据传输效率。

六、可靠性保障1. 内置温度传感器，实时监测芯片工作温度，保障芯片在适宜环境下运行。

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3. 经过严格的老化测试，确保产品在长时间使用下的可靠性。

M A X 1661/M A X 1662/M A X 1663Serial-to-Parallel/Parallel-to-Serial Converters and Load-Switch Controllers with SMBus Interface ABSOLUTE MAXIMUM RATINGS ELECTRICAL CHARACTERISTICS (V CC = +2.7V to +5.5V, T A = T MIN to T MAX , unless otherwise noted. Typical values are for T A = +25°C.) (Note 1)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.V CC to GND..............................................................-0.3V to +6V I/O to GND (I/O1, I/O2, I/O3)..................................-0.3V to +30V I/O Sink Current (I/O1, I/O2, I/O3), Internally Limited.............................................-1mA to +50mA Digital Inputs to GND (SMBCLK, SMBDATA,SMBSUS , ALERT ).................................................-0.3V to +6V ADD to GND...............................................-0.3V to (V CC + 0.3V)SMBDATA Current, ALERT Current....................-1mA to +50mA Continuous Power Dissipation (T A = +70°C)10-pin µMAX (derate 5.6mW/°C above +70°C)...........444mW Operating Temperature Range MAX166_EUB..................................................-40°C to +85°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CMAX1661/MAX1662/MAX1663Serial-to-Parallel/Parallel-to-Serial Converters and Load-Switch Controllers with SMBus Interface Note 1:Specifications from 0°C to -40°C are guaranteed by design, not production tested.Note 2:Supply current is specified for static state only.Note 3:The SMBus logic block is a static design that works with clock frequencies down to DC. While slow operation is possible, itviolates the 10kHz minimum clock frequency of the SMBus specifications, and may monopolize the bus.Note 4:Refer to Figures 2a and 2b for SMBus timing parameter definitions (write and read diagrams).Note 5:A transition must internally provide a hold time of 300ns to accommodate for the undefined region of the falling edge.Note 6:Refer to Figure 3 for the acknowledge timing diagram and t DV parameter definition.Note 7:Refer to Figure 5 for START-STOP interrupt timing diagrams and parameter definitions.Note 8:Refer to Figure 4 for I/O setup and hold timing parameter definitions.ELECTRICAL CHARACTERISTICS (continued)(V CC = +2.7V to +5.5V, T A = T MIN to T MAX , unless otherwise noted. Typical values are for T A = +25°C.) (Note 1)。

±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 TransceiversSWITCHING CHARACTERISTICS—MAX483E, MAX487E/MAX488E/MAX489E (V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)SWITCHING CHARACTERISTICS—MAX481E/MAX485E, MAX490E/MAX491E, MAX1487E(continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)2251000Figures 11 and 13, C L = 100pF, S2 closedFigures 11 and 13, C L = 100pF, S1 closedFigures 9 and 15, C L = 15pF, S2 closed,A -B = 2VCONDITIONSns 45100t ZH(SHDN)Driver Enable from Shutdown to Output High (MAX481E)ns Figures 9 and 15, C L = 15pF, S1 closed,B - A = 2V t ZL(SHDN)Receiver Enable from Shutdown to Output Low (MAX481E)ns 45100t ZL(SHDN)Driver Enable from Shutdown to Output Low (MAX481E)ns 2251000t ZH(SHDN)Receiver Enable from Shutdown to Output High (MAX481E)UNITS MIN TYP MAX SYMBOL PARAMETER t PLH t SKEW Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pF t PHL Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pF Driver Input to OutputDriver Output Skew to Outputns 20800ns ns 2000MAX483E/MAX487E, Figures 11 and 13,C L = 100pF, S2 closed t ZH(SHDN)Driver Enable from Shutdown to Output High 2502000ns 2500MAX483E/MAX487E,Figures 9 and 15,C L = 15pF, S1 closed t ZL(SHDN)Receiver Enable from Shutdownto Output Lowns 2500MAX483E/MAX487E,Figures 9 and 15,C L = 15pF, S2 closed t ZH(SHDN)Receiver Enable from Shutdown to Output High ns 2000MAX483E/MAX487E, Figures 11 and 13,C L = 100pF, S1 closed t ZL(SHDN)Driver Enable from Shutdown to Output Low ns 50200600MAX483E/MAX487E (Note 5) t SHDNTime to Shutdown t PHLt PLH , t PHL < 50% of data period Figures 9 and 15, C RL = 15pF, S2 closed Figures 9 and 15, C RL = 15pF, S1 closed Figures 9 and 15, C RL = 15pF, S2 closed Figures 9 and 15, C RL = 15pF, S1 closed Figures 11 and 13, C L = 15pF, S2 closed Figures 10 and 14, R DIFF = 54Ω,C L1= C L2= 100pF Figures 11 and 13, C L = 15pF, S1 closed Figures 11 and 13, C L = 100pF, S1 closed Figures 11 and 13, C L = 100pF, S2 closed CONDITIONS kbps 250f MAX2508002000Maximum Data Rate ns 2550t HZReceiver Disable Time from High ns 25080020002550t LZReceiver Disable Time from Low ns 2550t ZHReceiver Enable to Output High ns 2550t ZLReceiver Enable to Output Low ns ns 1003003000t HZ t SKDDriver Disable Time from HighI t PLH - t PHL I Differential Receiver Skew Figures 10 and 14, R DIFF = 54Ω,C L1= C L2= 100pF ns 3003000t LZ Driver Disable Time from Lowns 2502000t ZL Driver Enable to Output Lowns Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pF ns 2502000t R , t F 2502000Driver Rise or Fall Timens t PLHReceiver Input to Output 2502000t ZH Driver Enable to Output HighUNITS MIN TYP MAX SYMBOL PARAMETERMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E4±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 TransceiversFigure 6. IEC1000-4-2 ESD Test ModelFigure 8. Driver DC Test LoadFigure 7. IEC1000-4-2 ESD Generator Current WaveformFigure 9. Receiver Timing Test LoadFigure 4. Human Body ESD Test ModelFigure 5. Human Body Model Current Waveform MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E10。

Half-Duplex RS-485-/RS-422-Compatible Transceiver with AutoDirection Control MAX13487E/MAX13488E General DescriptionThe MAX13487E/MAX13488E +5V, half-duplex, ±15kV ESD-protected RS-485/RS-422-compatible transceivers feature one driver and one receiver. The MAX13487E/MAX13488E include a hot-swap capability to eliminate false transitions on the bus during power-up or live insertion.The MAX13487E/MAX13488E feature Maxim’s propri-etary AutoDirection control. This architecture makes the devices ideal for applications, such as isolated RS-485 ports, where the driver input is used in conjunction with the driver-enable signal to drive the differential bus.The MAX13487E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free trans-mission up to 500kbps. The MAX13488E driver slew rate is not limited, allowing transmit speeds up to 16Mbps.The MAX13487E/MAX13488E feature a 1/4-unit load receiver input impedance, allowing up to 128 trans-ceivers on the bus. These devices are intended for half-duplex communications. All driver outputs are protected to ±15kV ESD using the Human Body Model. The MAX13487E/MAX13488E are available in an 8-pin SO package. The devices operate over the extended -40°C to +85°C temperature range.Applications Isolated RS-485 InterfacesUtility MetersIndustrial ControlsIndustrial Motor DrivesAutomated HVAC SystemsBenefits and Features •AutoDirection Saves Space and BOM Cost •AutoDirection Enables Driver Automatically on Transmission, Eliminating an Opto or Other Discrete Means of Isolation •8-Pin SO Package •Robust Protection Features for Telecom, Industrial,and Isolated Applications •Hot-Swap Capability to Eliminate False Transitions on the Bus During Power-Up or Live Insertion •Extended ESD Protection for RS-485 I/O Pins (±15kV Human Body Model)•Options Optimize Designs for Speed or Errorless Data Transmission •Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission (MAX13487E)•High-Speed Version (MAX13488E) Allows for Transmission Speeds Up to 16Mbps •1/4-Unit Load, Allowing Up to 128 Transceivers on the Bus Ordering Information/Selector Guide+Note:All devices operate over the -40°C to +85°C temperature range.Pin Configuration/Typical Application Circuit appear at end of data sheet.Functional Diagram 19-0740; Rev 1; 2/15找MEMORY 、二三极管上美光存储MAX13487E/MAX13488E Half-Duplex RS-485-/RS-422-Compatible Transceiver with AutoDirection Control Integrated | 7Typical Operating Characteristics (continued)(V CC = +5.0V, T A = +25°C, unless otherwise noted.)RECEIVER PROPAGATION vs. TEMPERATURE(MAX13488E)TEMPERATURE (°C)R E C E I VE R P R O P A G A T I O N (n s )603510-1510203040-4085DRIVER PROPAGATION (500kbps)(MAX13487E)M A X 13487E t o c 17DI 2V/div A-B5V/div400ns/div DRIVER PROPAGATION (16Mbps)(MAX13488E)DI 2V/div A-B 5V/div 10ns/div RECEIVER PROPAGATION (16Mbps)(MAX13488E)MA X 13487E t o c 19B 2V/div RO 2V/div A2V/div10ns/div DRIVING 16nF (19.2kbps)(MAX13487E)M A X 13487E t o c 20DI2V/divA-B 5V/div10μs/div DRIVING 16nF (19.2kbps)(MAX13488E)M A X 13487E t o c 21DI2V/div A-B5V/div 10μs/div DRIVING 16nF (750kbps)(MAX13488E)M A X 13487E t o c 22DI 2V/div A-B 5V/div400ns/div。

General DescriptionDevices in the MAX3483E family (MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E) are ±15kV ESD-protected, +3.3V, low-power transceivers for RS-485 and RS-422 communications. Each device con-tains one driver and one receiver. The MAX3483E and MAX3488E feature slew-rate-limited drivers that minimize EMI and reduce reflections caused by improperly termi-nated cables, allowing error-free data transmission at data rates up to 250kbps. The partially slew-rate-limited MAX3486E transmits up to 2.5Mbps. The MAX3485E,MAX3490E, and MAX3491E transmit at up to 12Mbps.All devices feature enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 Air-Gap Discharge, ±8kV using IEC 1000-4-2 Contact Discharge, and ±15kV using the Human Body Model.Drivers are short-circuit current limited and are protect-ed against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if both inputs are open circuit.The MAX3488E, MAX3490E, and MAX3491E feature full-duplex communication, while the MAX3483E,MAX3485E, and MAX3486E are designed for half-duplex communication.ApplicationsTelecommunicationsIndustrial-Control Local Area Networks Transceivers for EMI-Sensitive Applications Integrated Services Digital Networks Packet SwitchingFeatureso ESD Protection for RS-485 I/O Pins±15kV—Human Body Model±8kV—IEC 1000-4-2, Contact Discharge ±15kV—IEC 1000-4-2, Air-Gap Discharge o Operate from a Single +3.3V Supply—No Charge Pump Required o Interoperable with +5V Logic o Guaranteed 12Mbps Data Rate (MAX3485E/MAX3490E/MAX3491E)o Slew-Rate Limited for Errorless Data Transmission (MAX3483E/MAX3488E) o 2nA Low-Current Shutdown Mode(MAX3483E/MAX3485E/MAX3486E/MAX3491E)o -7V to +12V Common-Mode Input Voltage Range o Full-Duplex and Half-Duplex Versions Available o Industry-Standard 75176 Pinout (MAX3483E/MAX3485E/MAX3486E)o Current-Limiting and Thermal Shutdown for Driver Overload ProtectionMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers________________________________________________________________Maxim Integrated Products119-1474; Rev 0; 4/99Selector GuideOrdering InformationOrdering Information continued at end of data sheet.For free samples & the latest literature: , or phone 1-800-998-8800.For small orders, phone 1-800-835-8769.M A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceiversABSOLUTE MAXIMUM RATINGSDC ELECTRICAL CHARACTERISTICS(V = +3.3V ±0.3V, T = T to T , unless otherwise noted. Typical values are at T = +25°C.)Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.Supply Voltage (V CC ).............................................................+7V Control Input Voltage (RE , DE).................................-0.3V to +7V Driver Input Voltage (DI)...........................................-0.3V to +7V Driver Output Voltage (A, B, Y, Z).......................-7.5V to +12.5V Receiver Input Voltage (A, B)..............................-7.5V to +12.5V Receiver Output Voltage (RO)....................-0.3V to (V CC + 0.3V)Continuous Power Dissipation (T A = +70°C)8-Pin SO (derate 5.88mW/°C above +70°C)..................471mW 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C).....727mW14-Pin SO (derate 8.33mW/°C above +70°C)................667mW 14-Pin Plastic DIP (derate 10mW/°C above +70°C)......800mW Operating Temperature RangesMAX34_ _ EC_ _...................................................0°C to +70°C MAX34_ _ EE_ _.................................................-40°C to +85°C Storage Temperature Range.............................-65°C to +150°C Lead Temperature (soldering, 10sec).............................+300°CMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceiversDC ELECTRICAL CHARACTERISTICS (continued)(V CC = +3.3V ±0.3V, T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)DRIVER SWITCHING CHARACTERISTICS—MAX3485E/MAX3490E/MAX3491E(V = +3.3V, T = +25°C.)DRIVER SWITCHING CHARACTERISTICS—MAX3486E(V = +3.3V, T = +25°C.)*MAX3488E and MAX3491E will be compliant to ±8kV per IEC 1000-4-2 Contact Discharge by September 1999.M A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers4_______________________________________________________________________________________DRIVER SWITCHING CHARACTERISTICS—MAX3483E/MAX3488E(V CC = +3.3V, T A = +25°C.)RECEIVER SWITCHING CHARACTERISTICS(V CC = +3.3V, T A = +25°C.)Note 1:∆V OD and ∆V OC are the changes in V OD and V OC , respectively, when the DI input changes state.Note 2:Measured on |t PLH (Y) - t PHL (Y)|and |t PLH (Z) - t PHL (Z)|.Note 3:The transceivers are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 80ns, thedevices are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the devices are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers_______________________________________________________________________________________5Typical Operating Characteristics(V CC = +3.3V, T A = +25°C, unless otherwise noted.)252015105000.51.01.52.02.53.53.0OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGEM A X 3483E -01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )-20-18-16-14-12-10-8-6-4-2000.51.01.52.02.53.53.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGEM A X 3483E -02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )3.003.053.103.153.203.253.30-40-20020406010080RECEIVER OUTPUT HIGH VOLTAGEvs. TEMPERATURETEMPERATURE (°C)O U T P U T H I G H V O L T A G E (V )00.10.20.30.40.50.60.70.8-40-2020406010080RECEIVER OUTPUT LOW VOLTAGEvs. TEMPERATURETEMPERATURE (°C)O U T P U T L O W V O L T A G E (V )2505075100125150175024681012OUTPUT CURRENT vs.DRIVER OUTPUT LOW VOLTAGEM A X 3483E -07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )100908070605040302010000.5 1.0 1.5 2.0 2.5 3.53.0DRIVER OUTPUT CURRENT vs.DIFFERENTIAL OUTPUT VOLTAGEM A X 3483E -05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )1.61.71.81.92.02.12.22.32.42.62.5-40-20020406010080DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURETEMPERATURE (°C)D I F FE R E N T I A L O U T P U T V O L T A G E (V )-100-80-60-40-20543210-7-6-3-4-5-2-1OUTPUT CURRENT vs.DRIVER OUTPUT HIGH VOLTAGEM A X 3483E -08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )M A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers0.80.70.91.01.11.2-40-2020406010080SUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (m A )Typical Operating Characteristics (continued)(V CC = +3.3V, T A = +25°C, unless otherwise noted.)0102030405060708010090-40-2020406010080SHUTDOWN CURRENT vs. TEMPERATUREM A X 3483E -10TEMPERATURE (°C)S H U T D O W N C U R R E N T (n A )Pin DescriptionMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers_______________________________________________________________________________________7Figure 2. MAX3488E/MAX3490E Pin Configuration and Typical Operating CircuitFigure 3. MAX3491E Pin Configuration and Typical Operating CircuitFigure 1. MAX3483E/MAX3485E/MAX3486E Pin Configuration and Typical Operating CircuitM A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers8_______________________________________________________________________________________Figure 4. Driver V OD and V OC Figure 7. Driver Differential Output Delay and Transition TimesFigure 6. Receiver V OH and V OLFigure 5. Driver V OD with Varying Common-Mode VoltageMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers_______________________________________________________________________________________9Figure 8. Driver Propagation TimesFigure 9. Driver Enable and Disable Times (t PZH , t PSH , t PHZ )Figure 10. Driver Enable and Disable Times (t PZL , t PSL , t PLZ )M A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers10______________________________________________________________________________________Figure 11. Receiver Propagation DelayFigure 12. Receiver Enable and Disable TimesNote 4: The input pulse is supplied by a generator with the following characteristics: f = 250kHz, 50% duty cycle, t r ≤6.0ns, Z O = 50Ω.Note 5: C L includes probe and stray capacitance._____________________Function TablesDevices with Receiver/Driver Enable(MAX3483E/MAX3485E/MAX3486E/MAX3491E)Table 1. Transmitting* B and A outputs are Z and Y, respectively, for full-duplex part (MAX3491E).X = Don’t care; High-Z = High impedanceTable 2. Receiving* DE is a “don’t care” (x) for the full-duplex part (MAX3491E).X = Don’t care; High-Z = High impedanceDevices without Receiver/Driver Enable(MAX3488E/MAX3490E)Table 3. TransmittingTable 4. Receiving___________Applications InformationThe MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E are low-power transceivers for RS-485 and RS-422 communications. The MAX3483E and MAX3488E can transmit and receive at data rates up to 250kbps, the MAX3486E at up to 2.5Mbps, and the MAX3485E/MAX3490E/MAX3491E at up to 12Mbps. The MAX3488E/MAX3490E/MAX3491E are full-duplex trans-ceivers, while the MAX3483E/MAX3485E/MAX3486E are half-duplex. Driver Enable (DE) and Receiver Enable (RE ) pins are included on the MAX3483E/MAX3485E/MAX3486E/MAX3491E. When disabled, the driver and receiver outputs are high impedance.Reduced EMI and Reflections (MAX3483E/MAX3486E/MAX3488E)The MAX3483E/MAX3488E are slew-rate limited, mini-mizing EMI and reducing reflections caused by improp-erly terminated cables. Figure 13 shows the driver output waveform of a MAX3485E/MAX3490E/MAX3491E transmitting a 125kHz signal, as well as the Fourier analysis of that waveform. High-frequency harmonics with large amplitudes are evident. Figure 14 shows the same information, but for the slew-rate-limited MAX3483E/MAX3488E transmitting the same signal. The high-frequency harmonics have much lower amplitudes,and the potential for EMI is significantly reduced.Low-Power Shutdown Mode(MAX3483E/MAX3485E/MAX3486E/MAX3491E)A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled (high impedance). In shutdown, the devices typically draw only 2nA of supply current.For these devices, the t PSH and t PSL enable times assume the part was in the low-power shutdown mode;the t PZH and t PZL enable times assume the receiver or driver was disabled, but the part was not shut down.MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers______________________________________________________________________________________11INPUTS OUTPUT A, B RO ≥+0.2V 1≤-0.2V 0Inputs Open1INPUT OUTPUTS DI Z Y 101015MHz 500kHz/div 05MHz500kHz/div Figure 13. Driver Output Waveform and FFT Plot of MAX3485E/MAX3490E/MAX3491E Transmitting a 125kHz Signal Figure 14. Driver Output Waveform and FFT Plot of MAX3483E/ MAX3488E Transmitting a 125kHz SignalM A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers12______________________________________________________________________________________Figure 17. MAX3483E/MAX3488E Driver Propagation Delay Figure 19. MAX3483E/MAX3488E System Differential Voltage at 125kHz Driving 4000 Feet of Cable Figure 20. MAX3485E/MAX3490E/MAX3491E System Differential Voltage at 125kHz Driving 4000 Feet of CableDriver-Output Protection Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). In addition, a thermal shut-down circuit forces the driver outputs into a high-imped-ance state if the die temperature rises excessively.Propagation Delay Figures 15–18 show the typical propagation delays. Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle).The receiver skew time, |t PRLH- t PRHL|, is under 10ns (20ns for the MAX3483E/MAX3488E). The driver skew times are 8ns for the MAX3485E/MAX3490E/MAX3491E, 12ns for the MAX3486E, and typically under 50ns for the MAX3483E/MAX3488E.Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 21 for an example of a line repeater.Figures 19 and 20 show the system differential voltage for parts driving 4000 feet of 26AWG twisted-pair wire at 125kHz into 120Ωloads.For faster data rate transmission, please consult the fac-tory.±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MAX3483E family of devices have extra protection against static electricity. Maxim’s engineers have developed state-of-the-art structures to protect these pins against ESD of ±15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, Maxim’s E versions keep working without latchup or damage.ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to the following limits:1)±15kV using the Human Body Model2)±8kV using the Contact-Discharge method specifiedin IEC 1000-4-23)±15kV using IEC 1000-4-2’s Air-Gap method.ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results.Human Body Model Figure 22a shows the Human Body Model and Figure 22b shows the current waveform it generates when dis-charged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of inter-est, which is then discharged into the test device through a 1.5kΩresistor.IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifi-cally refer to integrated circuits. The MAX3483E family of devices helps you design equipment that meets Level 4 (the highest level) of IEC 1000-4-2, without the need for additional ESD-protection components.The major difference between tests done using the Human Body Model and IEC 1000-4-2 is higher peak current in IEC 1000-4-2, because series resistance is lower in the IEC 1000-4-2 model. Hence, the ESD with-stand voltage measured to IEC 1000-4-2 is generally lower than that measured using the Human Body Model. Figure 23a shows the IEC 1000-4-2 model, and Figure 23b shows the current waveform for the ±8kV IEC 1000-4-2, Level 4 ESD contact-discharge test.Figure 21. Line Repeater for MAX3488E/MAX3490E/MAX3491EMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers ______________________________________________________________________________________13M A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491EThe air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized.Machine ModelThe Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resis-tance. Its objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. Of course, all pins require this protection, not just RS-485 inputs and outputs.Typical ApplicationsThe MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 24 and 25 show typical net-work applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 21.To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited MAX3483E/MAX3488E and the partially slew-rate-limited MAX3486E are more tolerant of imperfect termination.3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers14______________________________________________________________________________________Figure 22a. Human Body ESD Test ModelFigure 22b. Human Body Current WaveformFigure 23a. IEC 1000-4-2 ESD Test ModelFigure 23b. IEC 1000-4-2 ESD Generator Current WaveformMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceivers______________________________________________________________________________________15Figure 25. MAX3488E/MAX3490E/MAX3491E Full-Duplex RS-485 NetworkFigure 24. MAX3483E/MAX3485E/MAX3486E Typical RS-485 NetworkM A X 3483E /M A X 3485E /M A X 3486E /M A X 3488E /M A X 3490E /M A X 3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited T rue RS-485/RS-422 T ransceiversTRANSISTOR COUNT: 761Chip InformationOrdering Information (continued)Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.16____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600©1999 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.。

ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491E CIRCUIT DESCRIPTIONThe ADM34xxE are low power transceivers for RS-485 and RS­422 communications. The ADM3483E/ADM3488E operate at data rates up to 250 kbps. The ADM3486E operates at data rates up to 2.5 Mbps, and the ADM3490E/ADM3491E transmit at up to 12 Mbps. The ADM3488E/ADM3490E/ADM3491E are full-duplex transceivers, and the ADM3483E/ADM3486E are half duplex. Driver enable (DE) and receiver enable (RE) pins are included on the ADM3483E/ADM3486E/ADM3491E. When disabled, the driver and receiver outputs are high impedance. DEVICES WITH RECEIVER/DRIVER ENABLE—ADM3483E/A DM3486E/A DM3491E1 ADM3483E and ADM3486E only.2 ADM3491E only.3 X = don’t care.4 High-Z = high impedance.1 ADM3483E and ADM3486E only.2 ADM3491E only.3 X = don’t care.4 High-Z = high impedance.DEVICES WITHOUT RECEIVER/DRIVER ENABLE―ADM3488E/A DM3490ETable 11. Transmitting Truth TableTransmitting Input Transmitting OutputsDI ZY1010 10Table 12. Receiving Truth TableReceiving Input Receiving Output A – BRO≥ +0.2 V 1≤ −0.2 V 0Inputs open 1LOW POWER SHUTDOWN MODE—ADM3483E/ ADM3486E/A DM3491EThe ADM3483E/ADM3486E/ADM3491E are put into a low power shutdown mode by bringing both RE high and DE low. The devices do not shut down unless both the driver and the receiver are disabled (high impedance). In shutdown mode, the devices typically draw less than 1 μA of supply current. For these devices, the t PSH and the t PSL enable times assume the part was in the low power shutdown mode; the t PZH and the t PZL enable times assume the receiver or the driver was disabled, but the part was not shut down.DRIVER OUTPUT PROTECTIONThe ADM34xxE family implements two ways to prevent excessive output current and power dissipation caused by faults or by bus contention. A current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see the Typical Performance Characteristics section). In addition, a thermal shutdown circuit forces the driver outputs into a high impedance state if the die temperature rises excessively. PROPAGATION DELAYFigure 11, Figure 14, Figure 26, and Figure 27 show the typical propagation delays. Skew time is simply the difference between the low-to-high and the high-to-low propagation delays. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle).The receiver skew time, |t PRHL – t PRHL|, is under 10 ns (20 ns for the ADM3483E/ADM3488E). The driver skew time is 8 ns for the ADM3490E/ADM3491E, 12 ns for the ADM3486E, and typically under 50 ns for the ADM3483E/ADM3488E.LINE LENGTH VS. DATA RATEThe RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, Figure 34 illustrates an example of a line repeater.ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491E±15 kV ESD PROTECTIONTwo coupling methods are used for ESD testing: con-tact discharge and air-gap discharge. Contact dischargecalls for a direct connection to the unit being tested. Air-gap discharge uses a higher test voltage but does not makedirect contact with the test unit. With air-gap discharge,the discharge gun is moved toward the unit under test,developing an arc across the air gap, therefore the term air- gap discharge. This method is influenced by humidity, temperature, barometric pressure, distance, and rate of closure of the discharge gun. The contact discharge method, while less realistic, is more repeatable and is gaining acceptance and preference over the air-gap method.Although very little energy is contained within an ESD pulse, the extremely fast rise time, coupled with high voltages, can cause failures in unprotected semiconductors. Catastrophic destruction can occur immediately as a result of arcing or heating. Even if catastrophic failure does not occur immediately, the device can suffer from parametric degradation that can result in degraded performance. The cumulative effects of continuous exposure can eventually lead to complete failure. Input/output lines are particularly vulnerable to ESD damage. Simply touching or connecting an input/output cable can result in a static discharge that can damage or completely destroy the interface product connected to the input/output port. It is extremely important, therefore, to have high levels of ESD protection on the input/output lines.The ESD discharge can induce latch-up in the device under test, so it is important that ESD testing on the input/output pins be carried out while device power is applied. This type of testing is more representative of a real-world input/output discharge, which occurs when the equipment is operating normally.The transmitter outputs and receiver inputs of the ADM34xxE family are characterized for protection to a ±15 kV limit using the human body model.HUMAN BODY MODELFigure 30 shows the human body model and the current wave-form it generates when discharged into a low impedance. This model consists of a 100 pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5 kΩ resistor.I6284-16 Figure 30. Human Body Model and Current Waveform TYPICAL APPLICATIONSThe ADM3483E/ADM3486E/ADM3491E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. The ADM3488E/ADM3490E full-duplex transceiver is designed to be used in a daisy-chain network topology or in a point-to-point application (see Figure 32). The ADM3483E/ADM3486E are half-duplex RS-485 transceivers that can be used in a multidrop bus configuration, as shown in Figure 31. The ADM3488E/ADM3490E/ADM3491E can also be used as a line repeater, for use with cable lengths longer than 4000 feet, as shown in Figure 34. To minimize reflections, the line must be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible.ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491ENOTES1.MAXIMUM NUMBER OF TRANSCEIVERS ON BUS:32.2.R T IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE USED.06284-017Figure 31. ADM3483E/ADM3486E Typical Half-Duplex RS-485 NetworkADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491ENOTES1.MAXIMUM NUMBER OF NODES: 32.2. R T IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE USED.RODIDE MASTERSLAVERE06284-019Figure 33. ADM3491E Full-Duplex RS-485 NetworkDATA INDATA OUT06284-020Figure 34. Line Repeater for ADM3488E/ADM3490E/ADM3491EADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491E OUTLINE DIMENSIONSCONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES)ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.COMPLIANT TO JEDEC STANDARDS MS-012-AA060506-A0.17 (0.0067)Figure 35. 8-Lead Standard Small Outline Package [SOIC_N]Narrow Body(R-8)Dimensions shown in millimeters and (inches)CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES)ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.COMPLIANT TO JEDEC STANDARDS MS-012-AB060606-AFigure 36. 14-Lead Standard Small Outline Package [SOIC_N]Narrow Body (R-14)Dimensions shown in millimeters and (inches)ORDERING GUIDEModelTemperature RangePackage DescriptionPackage Option Ordering Quantity ADM3483EARZ 1–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 ADM3483EARZ-REEL71–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 1,000 ADM3486EARZ 1–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 ADM3486EARZ-REEL71–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 1,000 ADM3488EARZ 1–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 ADM3488EARZ-REEL71–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 1,000 ADM3490EARZ 1–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 ADM3490EARZ-REEL71–40°C to +85°C 8-Lead Standard Small Outline Package (SOIC_N) R-8 1,000 ADM3491EARZ 1–40°C to +85°C 14-Lead Standard Small Outline Package (SOIC_N) R-14 ADM3491EARZ-REEL71–40°C to +85°C14-Lead Standard Small Outline Package (SOIC_N) R-141,0001Z = Pb-free part.。

Figure 22. MAX3488/MAX3490/MAX3491 Full-Duplex RS-485 NetworkFigure 23. Line Repeater for MAX3488/MAX3490/MAX3491MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX34913.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 TransceiversLine Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Figure 23.Figures 19 and 20 show the system differential voltage for parts driving 4000 feet of 26AWG twisted-pair wire at 125kHz into 120Ω loads.Typical ApplicationsThe MAX3483, MAX3485, MAX3486, MAX3488, MAX3490, and MAX3491 transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 21 and 22 show typical net-work applications circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet, as shown in Figure 23.To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as pos-sible. The slew-rate-limited MAX3483/MAX3488 and the partially slew-rate-limited MAX3486 are more tolerant of imperfect termination.MAX3483/MAX3485/MAX3486/MAX3488/MAX3490/MAX34913.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers Figure 21. MAX3483/MAX3485/MAX3486 Typical RS-485 Network Driver Output ProtectionExcessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics ). In addition, a thermal shut-down circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively.Propagation Delay Figures 15–18 show the typical propagation delays. Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle).The receiver skew time, |t PRLH - t PRHL |, is under 10ns (20ns for the MAX3483/MAX3488). The driver skew times are 8ns for the MAX3485/MAX3490/MAX3491, 11ns for the MAX3486, and typically under 100ns for the MAX3483/MAX3488.。

M A X 1951/M A X 1952Typical Operating Characteristic s), the controllerresponds by regulating the output voltage back to itsnominal state. The controller response time depends onthe closed-loop bandwidth. A higher bandwidth yieldsa faster response time, thus preventing the output fromdeviating further from its regulating value.Compensation DesignThe double pole formed by the inductor and outputcapacitor of most voltage-mode controllers introduces a large phase shift, that requires an elaborate compensa-tion network to stabilize the control loop. The MAX1951/MAX1952 utilize a current-mode control scheme that reg-ulates the output voltage by forcing the required currentthrough the external inductor, eliminating the double polecaused by the inductor and output capacitor, and greatlysimplifying the compensation network. A simple type 1compensation with single compensation resistor (R 1) andcompensation capacitor (C2) creates a stable and high-bandwidth loop.An internal transconductance error amplifier compen-sates the control loop. Connect a series resistor andcapacitor between COMP (the output of the error ampli-fier) and GND to form a pole-zero pair. The externalinductor, internal current-sensing circuitry, outputcapacitor, and the external compensation circuit deter-mine the loop system stability. Choose the inductor andoutput capacitor based on performance, size, and cost.Additionally, select the compensation resistor andcapacitor to optimize control-loop stability. The compo-nent values shown in the typical application circuit(Figure 2) yield stable operation over a broad range ofinput-to-output voltages.The basic regulator loop consists of a power modulator,an output feedback divider, and an error amplifier. Thepower modulator has DC gain set by gmc x RLOAD ,with a pole-zero pair set by R LOAD , the output capaci-tor (COUT ), and its ESR. The following equations definethe power modulator:Modulator gain:G MOD = ΔV OUT /ΔV COMP = gmc x R LOADModulator pole frequency:fp MOD = 1 / (2 x πx C OUT x (R LOAD +ESR))Modulator zero frequency:fz ESR = 1 /(2 x πx C OUT x ESR)where, R LOAD = V OUT /I OUT(MAX), and gmc = 4.2S.The feedback divider has a gain of G FB = V FB / V OUT ,where VFB is equal to 0.8V. The transconductance erroramplifier has a DC gain, G EA(DC),of 70dB. The com-pensation capacitor, C2,and the output resistance ofthe error amplifier, R OEA (20M Ω), set the dominant pole. C 2and R 1 set a compensation zero. Calculate the dominant pole frequency as:fp EA = 1/(2πx C C x R OEA )Determine the compensation zero frequency is:fz EA = 1/(2πx C C x R C )F or best stability and response performance, set the closed-loop unity-gain frequency much higher than the modulator pole frequency. In addition, set the closed-loop crossover unity-gain frequency less than, or equal to, 1/5 of the switching frequency. However, set the maximum zero crossing frequency to less than 1/3 of the zero frequency set by the output capacitance and its ESR when using POSCAP, SPCAP, OSCON, or other electrolytic capacitors.The loop-gain equation at the unity-gain frequency is:G EA(fc) x G MOD(fc) x V FB /V OUT = 1where G EA(fc )= gm EA x R 1, and G MOD(fc)= gmc x R LOAD x fp MOD /f C, where gm EA = 60µS .R 1calculated as:R 1= V OUT x K/(gm EA x V FB x G MOD(fc))where K is the correction factor due to the extra phase introduced by the current loop at high frequencies (>100kHz). K is related to the value of the output capacitance (see Table 1 for values of K vs. C). Set the error-amplifier compensation zero formed by R 1and C 2at the modulator pole frequency at maximum load. C 2is calculated as follows:C 2= (V OUT x C OUT /(R 1 x I OUT(MAX))As the load current decreases, the modulator pole also decreases; however, the modulator gain increases accordingly, resulting in a constant closed-loop unity-gain frequency. Use the following numerical example to calculate R 1and C 2values of the typical application circuit of Figure 2a.V OUT = 1.5V I OUT(MAX)= 1.5A C OUT = 10µF R ESR = 0.010Ωgm EA = 60µS找MEMORY 、二三极管上美光存储1MHz, All-Ceramic, 2.6V to 5.5V Input, 2A PWM Step-Down DC-to-DC Regulatorsgmc = 4.2Sf SWITCH= 1MHzR LOAD= V OUT/I OUT(MAX)= 1.5V/1.5 A = 1Ωfp MOD= [1/(2πx C OUT x (R LOAD + R ESR)]= [1/(2 x π×10 ×10-6x (1 + 0.01)] = 15.76kHz. fz ESR= [1/(2πxC OUT R ESR)]= [1/(2 x π×10 ×10-6×0.01)] = 1.59MHz.For 2µH output inductor, pick the closed-loop unity-gain crossover frequency (f C) at 200kHz. Determine the power modulator gain at f C:G MOD(fc)= gmc ×R LOAD×fp MOD/f C= 4.2 ×1 ×15.76kHz/200kHz= 0.33then:R1= V O x K/(gm EA x V FB x G MOD(fc)) = (1.5 x 0.55)/(60 ×10-6 ×0.8 ×0.33) ≈51.1kΩ(1%)C2= (V OUT×C OUT)/(R×I OUT(max))= (1.5 × 10 × 10-6)/(51.1k ×1.5)≈196pF, choose 220pF, 10%Applications InformationPCB Layout Considerations Careful PCB layout is critical to achieve clean and sta-ble operation. The switching power stage requires par-ticular attention. Follow these guidelines for good PCB layout:1)Place decoupling capacitors as close to the IC aspossible. Keep power ground plane (connected to PGND) and signal ground plane (connected to GND) separate.2)Connect input and output capacitors to the powerground plane; connect all other capacitors to the signal ground plane.3)Keep the high-current paths as short and wide aspossible. Keep the path of switching current (C1 to INand C1 to PGND) short. Avoid vias in the switchingpaths.4)If possible, connect IN, LX, and PGND separately toa large copper area to help cool the IC to furtherimprove efficiency and long-term reliability.5)Ensure all feedback connections are short anddirect. Place the feedback resistors as close to theIC as possible.6)Route high-speed switching nodes away from sensi-tive analog areas (FB, COMP).Thermal ConsiderationsThe MAX1951 uses a fused-lead 8-pin SO package witha R THJC rating of 32°C/W. The MAX1951 EV kit layout is optimized for 1.5A. The typical application circuit shownin Figure 2c was tested with the existing MAX1951 EV kitlayout at +85°C ambient temperature, and GND lead temperature was measured at +113°C for a typical device. The estimated junction temperature was+138°C. Thermal performance can be further improvedwith one of the following options:1)Increase the copper areas connected to GND, LX,and IN.2)Provide thermal vias next to GND and IN, to theground plane and power plane on the back side ofPCB, with openings in the solder mask next to thevias to provide better thermal conduction.3)Provide forced-air cooling to further reduce casetemperature.MAX1951/MAX1952。

(V CC = +3.3V, T A = +25°C)Note 1: ∆V OD and ∆V OC are the changes in V OD and V OC , respectively, when the DI input changes state.Note 2: Measured on |t PLH (Y) - t PHL (Y)| and |t PLH (Z) - t PHL (Z)|.Note 3: The transceivers are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 80ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the parts are guaranteed tohave entered shutdown. See Low-Power Shutdown Mode section.PARAMETERSYMBOL CONDITIONS MIN TYP MAX UNITS Time to Shutdownt SHDN MAX3483E/MAX3485E/MAX3486E/MAX3491E only (Note 3)80190300ns Receiver Propagation Delay,Low-to-High Levelt RPLH V ID = 0 to 3.0, C L = 15pF, Figure 11256290ns MAX3483E/MAX3488E 2575120Receiver Propagation Delay,High-to-Low Levelt RPHL V ID = 0 to 3.0, C L = 15pF, Figure 11256290ns MAX3483E/MAX3488E 2575120|t PLH - t PHL | ReceiverPropagation Delay Skewt RPDS V ID = 0 to 3.0, C L = 15pF, Figure 116±10ns MAX3483E/MAX3488E 12±20Receiver Output Enable Timeto Low Levelt PRZL C L = 15pF, Figure 12,MAX3483E/85E/86E/91E only 2550ns Receiver Output Enable Timeto High Levelt PRZH C L = 15pF, Figure 12,MAX3483E/85E/86E/91E only 2550ns Receiver Output DisableTime from High Levelt PRHZ C L = 15pF, Figure 12,MAX3483E/85E/86E/91E only 2545ns Receiver Output DisableTime from Low Levelt PRLZ C L = 15pF, Figure 12,MAX3483E/85E/86E/91E only 2545ns Receiver Output Enable Timefrom Shutdown to Low Levelt PRSL C L = 15pF, Figure 12,MAX3483E/85E/86E/91E only 7201400ns Receiver Output Enable Timefrom Shutdown to High Level t PRSH C L = 15pF, Figure 12,MAX3483E/85E/86E/91E only 7201400nsMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers Receiver Switching CharacteristicsFigure 24. MAX3483E/MAX3485E/MAX3486E Typical RS-485 NetworkFigure 25. MAX3488E/MAX3490E/MAX3491E Full-Duplex RS-485 NetworkMAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E3.3V-Powered, ±15kV ESD-Protected, 12Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers。