MAX5418NETA+T中文资料

General DescriptionThe MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environ-ments. Each driver output and receiver input is protected against ±15kV electro-static discharge (ESD) shocks,without latchup. These parts contain one driver and one receiver. The MAX483E, MAX487E, MAX488E, and MAX489E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly termi-nated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481E,MAX485E, MAX490E, MAX491E, and MAX1487E are not limited, 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 disabled drivers (see Selector Guide ). Additionally, the MAX481E,MAX483E, and MAX487E have a low-current shutdown mode in which they consume only 0.5µA. All parts oper-ate from a single +5V supply.Drivers are short-circuit current limited, and are protected against excessive power dissipation by thermal shutdown circuitry that places their outputs into a high-impedance state. 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-load receiver input impedance, allowing up to 128 trans-ceivers on the bus. The MAX488E–MAX491E are designed for full-duplex communications, while the MAX481E, MAX483E, MAX485E, MAX487E, and MAX1487E 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 Transceivers Low-Power RS-422 Transceivers Level TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area NetworksNext-Generation Device Features♦For Fault-Tolerant Applications:MAX3430: ±80V Fault-Protected, Fail-Safe, 1/4-Unit Load, +3.3V, RS-485 TransceiverMAX3080–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 TransceiversMAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 PackageMAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422True Fail-Safe ReceiversMAX3030E–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 TransceiversMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers________________________________________________________________Maxim Integrated Products 1Ordering Information19-0410; Rev 4; 10/03For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .Ordering Information continued at end of data sheet.Selector Guide appears at end of data sheet .M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers2_______________________________________________________________________________________Supply Voltage (V CC ) (12V)Control Input Voltage (–R —E –, DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (Y, Z; A, B)..........................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO)....................-0.5V to (V CC + 0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW 14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW Operating Temperature RangesMAX4_ _C_ _/MAX1487EC_ A.............................0°C to +70°C MAX4__E_ _/MAX1487EE_ A...........................-40°C to +85°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CDC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)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.ABSOLUTE MAXIMUM RATINGSPARAMETERSYMBOL MINTYPMAX UNITS Driver Common-Mode Output VoltageV OC 3V Change in Magnitude of Driver Differential Output Voltage for Complementary Output States ∆V OD 0.2V Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States ∆V OD 0.2V Input High Voltage V IH 2.0V Input Low Voltage V IL 0.8V Input CurrentI IN1±2µADifferential Driver Output (no load)V OD15V 2V Differential Driver Output (with load)V OD2 1.551.0-0.8mA0.25mA -0.2Receiver Differential Threshold Voltage-0.20.2V Receiver Input Hysteresis ∆V TH 70mV Receiver Output High Voltage V OH 3.5Receiver Output Low Voltage V OL 0.4V Three-State (high impedance)Output Current at ReceiverI OZR±1µA 12k ΩCONDITIONSDE = 0V;V CC = 0V or 5.25V,all devices except MAX487E/MAX1487E R = 27Ωor 50Ω, Figure 8R = 27Ωor 50Ω, Figure 8R = 27Ωor 50Ω, Figure 8DE, DI, –R —E–MAX487E/MAX1487E,DE = 0V, V CC = 0V or 5.25VDE, DI, –R —E–DE, DI, –R —E–-7V ≤V CM ≤12V V CM = 0VI O = -4mA, V ID = 200mV I O = 4mA, V ID = -200mV R = 50Ω(RS-422)0.4V ≤V O ≤2.4VR = 27Ω(RS-485), Figure 8-7V ≤V CM ≤12V, all devices except MAX487E/MAX1487EReceiver Input Resistance R IN-7V ≤V CM ≤12V, MAX487E/MAX1487E48k ΩV TH I IN2Input Current (A, B)V IN = 12V V IN = -7V V IN = 12V V IN = -7VVMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 TransceiversSWITCHING CHARACTERISTICS—MAX481E/MAX485E, MAX490E/MAX491E, MAX1487EDC ELECTRICAL CHARACTERISTICS (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers4_______________________________________________________________________________________SWITCHING 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 closed Figures 11 and 13, C L = 100pF, S1 closed Figures 9 and 15, C L = 15pF, S2 closed,A - B = 2VCONDITIONSns 45100t ZH(SHDN)Driver Enable from Shutdown toOutput High (MAX481E)nsFigures 9 and 15, C L = 15pF, S1 closed,B - A = 2Vt ZL(SHDN)Receiver Enable from Shutdownto Output Low (MAX481E)ns 45100t ZL(SHDN)Driver Enable from Shutdown toOutput Low (MAX481E)ns 2251000t ZH(SHDN)Receiver Enable from Shutdownto Output High (MAX481E)UNITS MINTYP MAX SYMBOLPARAMETERt PLH t SKEW Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pFt PHL Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pFDriver Input to Output Driver Output Skew to Output ns 20800ns ns 2000MAX483E/MAX487E, Figures 11 and 13,C L = 100pF, S2 closedt ZH(SHDN)Driver Enable from Shutdown to Output High2502000ns2500MAX483E/MAX487E, Figures 9 and 15,C L = 15pF, S1 closedt ZL(SHDN)Receiver Enable from Shutdown to Output Lowns 2500MAX483E/MAX487E, Figures 9 and 15,C L = 15pF, S2 closedt ZH(SHDN)Receiver Enable from Shutdown to Output Highns 2000MAX483E/MAX487E, Figures 11 and 13,C L = 100pF, S1 closedt ZL(SHDN)Driver Enable from Shutdown to Output Lowns 50200600MAX483E/MAX487E (Note 5)t SHDN Time to Shutdownt PHL t 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= 100pFFigures 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 CONDITIONSkbps 250f MAX 2508002000Maximum Data Rate ns 2550t HZ Receiver Disable Time from High ns 25080020002550t LZ Receiver Disable Time from Low ns 2550t ZH Receiver Enable to Output High ns 2550t ZL Receiver Enable to Output Low ns ns 1003003000t HZ t SKD Driver Disable Time from High I t PLH - t PHL I DifferentialReceiver SkewFigures 10 and 14, R DIFF = 54Ω,C L1= C L2= 100pFns 3003000t LZ Driver Disable Time from Low ns 2502000t ZL Driver Enable to Output Low ns Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pFns 2502000t R , t F 2502000Driver Rise or Fall Time ns t PLH Receiver Input to Output2502000t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers_______________________________________________________________________________________505101520253035404550OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGEM A X 481E -01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )1.52.02.51.00.50.10.20.30.40.50.60.70.80.9-60-2060RECEIVER OUTPUT LOW VOLTAGEvs. TEMPERATURETEMPERATURE (°C)O U T P U T L O W V O L T A G E (V )20100-4040800-5-10-15-20-251.53.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGEM A X 481E -02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )5.04.54.02.02.53.53.03.23.43.63.84.04.24.44.64.8-60-2060RECEIVER OUTPUT HIGH VOLTAGEvs. TEMPERATURETEMPERATURE (°C)O U T P U T H I G H V O L T A G E (V )20100-4040800102030405060708090DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGEM A X 481E -05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )1.52.0 2.53.0 3.54.0 4.51.00.50__________________________________________Typical Operating Characteristics(V CC = 5V, T A = +25°C, unless otherwise noted.)NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICSNote 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to deviceground unless otherwise specified.Note 2:All typical specifications are given for V CC = 5V and T A = +25°C.Note 3:Supply current specification is valid for loaded transmitters when DE = 0V.Note 4:Applies to peak current. See Typical Operating Characteristics.Note 5:The MAX481E/MAX483E/MAX487E are put into shutdown by bringing –R —E –high and DE low. If the inputs are in this state forless than 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section.M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers6___________________________________________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 5V, T A = +25°C, unless otherwise noted.)1.52.32.22.12.01.91.81.71.6-60-2060DRIVER 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 )20100-404080020406080100120140OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGEM A X 481E -07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )246810120-10-20-30-40-50-60-70-80-90-100-8-2OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGEM A X 481E -08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )642-6-400100200300400500600-60-2060MAX481E/MAX485E/MAX490E/MAX491E SUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20100-4040800100200300400500600-60-2060MAX483E/MAX487E–MAX489E SUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20100-404080100200300400500600-60-2060MAX1487ESUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20100-404080±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers_______________________________________________________________________________________7MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E______________________________________________________________Pin DescriptionM A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers8_________________________________________________________________________________________________Function Tables (MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E) Table 1. Transmitting__________Applications Information The MAX481E/MAX483E/MAX485E/MAX487E–MAX491E and MAX1487E are low-power transceivers for RS-485 and RS-422 communications. These “E” versions of the MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 provide extra protection against ESD. The rugged MAX481E, MAX483E, MAX485E, MAX497E–MAX491E, and MAX1487E are intended for harsh envi-ronments where high-speed communication is important. These devices eliminate the need for transient suppres-sor diodes and the associated high capacitance loading. The standard (non-“E”) MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are recommended for applications where cost is critical.The MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E can transmit and receive at data rates up to 2.5Mbps, while the MAX483E, MAX487E, MAX488E, and MAX489E are specified for data rates up to 250kbps. The MAX488E–MAX491E are full-duplex transceivers, while the MAX481E, MAX483E, MAX487E, and MAX1487E are half-duplex. In addition, driver-enable (DE) and receiver-enable (RE) pins are included on the MAX481E, MAX483E, MAX485E, MAX487E, MAX489E, MAX491E, and MAX1487E. When disabled, the driver and receiver outputs are high impedance.±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electro-static discharges encountered during handling and assembly. The driver outputs and receiver inputs have extra protection against static electricity. Maxim’s engi-neers 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 MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E keep working without latchup.ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to ±15kV using the Human Body Model.Other ESD test methodologies include IEC10004-2 con-tact discharge and IEC1000-4-2 air-gap discharge (for-merly IEC801-2).ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test set-up, test methodology, and test results.Human Body Model Figure 4 shows the Human Body Model, and Figure 5 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.IEC1000-4-2 The IEC1000-4-2 standard covers ESD testing and per-formance of finished equipment; it does not specifically refer to integrated circuits (Figure 6).MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers_______________________________________________________________________________________9M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers10______________________________________________________________________________________Figure 8. Driver DC Test LoadFigure 9. Receiver Timing Test LoadMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers______________________________________________________________________________________11Figure 10. Driver/Receiver Timing Test Circuit Figure 11. Driver Timing Test LoadFigure 12. Driver Propagation DelaysFigure 13. Driver Enable and Disable Times (except MAX488E and MAX490E)Figure 14. Receiver Propagation DelaysFigure 15. Receiver Enable and Disable Times (except MAX488E and MAX490E)M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers12______________________________________________________________________________________The 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 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 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 BusThe 48k Ω, 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 (12k Ωinput 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 12k Ωreceiver 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. Figure 16shows 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.Figure 17 shows the same information displayed for a MAX483E, MAX487E, MAX488E, or MAX489E transmit-ting under the same conditions. Figure 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.For 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 ).500kHz/div0Hz5MHz 10dB/div Figure 16. Driver Output Waveform and FFT Plot ofMAX485E/MAX490E/MAX491E/MAX1487E Transmitting a 150kHz Signal500kHz/div0Hz5MHz10dB/divFigure 17. Driver Output Waveform and FFT Plot ofMAX483E/MAX487E–MAX489E Transmitting a 150kHz SignalIt takes the drivers and receivers longer to become enabled from the low-power shutdown state (t ZH(SHDN), t ZL(SHDN)) than from the operating mode (t ZH, t ZL). (The parts are in operating mode if the RE, DE inputs equal a logical 0,1 or 1,1 or 0, 0.)Driver 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 Many digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 19–22 using Figure 18’s test circuit.The difference in receiver delay times, t PLH- t PHL, is typically under 13ns for the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E, and is typically less than 100ns for the MAX483E and MAX487E–MAX489E.The driver skew times are typically 5ns (10ns max) for the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E, and are typically 100ns (800ns max) for the MAX483E and MAX487E–MAX489E.Typical Applications The MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 25 and 26 show typical net-work application circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet. 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 possi-ble. The slew-rate-limited MAX483E and MAX487E–MAX489E are more tolerant of imperfect termination. Bypass the V CC pin with 0.1µF.Isolated RS-485 For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. Figures 23 and 24 show the system differen-tial voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 100Ωloads.Figure 18. Receiver Propagation Delay Test CircuitMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers ______________________________________________________________________________________13M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers14______________________________________________________________________________________25ns/div 5V/divRO B A500mV/div Figure 19. MAX481E/MAX485E/MAX490E/MAX1487E Receiver t PHL25ns/div5V/div ROBA500mV/divFigure 20. MAX481E/MAX485E/MAX490E/MAX491E/MAX1487E Receiver t PLH200ns/div 5V/divRO B A500mV/div Figure 21. MAX483E/MAX487E–MAX489E Receiver t PHL200ns/div5V/div ROBA500mV/divFigure 22. MAX483E/MAX487E–MAX489E Receiver t PLH2µs/div DO 0V0V5V5V -1V 0DIV A - V BFigure 23. MAX481E/MAX485E/MAX490E/MAX491E/MAX1487E System Differential Voltage at 110kHz Driving 4000ft of Cable 2µs/divDO0V0V 5V 5V -1V1V0DIV B - V AFigure 24. MAX483E/MAX1487E–MAX489E System Differential Voltage at 110kHz Driving 4000ft of CableMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers______________________________________________________________________________________15Figure 26. MAX488E–MAX491E Full-Duplex RS-485 NetworkFigure 25. MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E Typical Half-Duplex RS-485 NetworkM A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers 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©2003 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.Package InformationFor the latest package outline information, go to /packages .Ordering Information (continued)Selector GuideChip InformationTRANSISTOR COUNT: 295。

General DescriptionThe MAX5432–MAX5435 nonvolatile, linear-taper, digi-tal potentiometers perform the function of a mechanical potentiometer, but replace the mechanics with a simple 2-wire serial interface. Each device performs the same function as a discrete potentiometer or a variable resis-tor and has 32 tap points.The MAX5432–MAX5435 feature an internal, nonvolatile,electrically erasable programmable read-only memory (EEPROM) that returns the wiper to its previously stored position at power-up. The fast-mode I 2C †-compatible serial interface allows communication at data rates up to 400kbps, minimizing board space and reducing inter-connection complexity. Each device is available with one of four factory-preset I 2C addresses (see the Selector Guide ).Use the MAX5432–MAX5435 in applications requiring digitally controlled resistors. Two resistance values are available (50k Ωand 100k Ω) in a voltage-divider or vari-able resistor configuration. The nominal resistor temper-ature coefficient is 35ppm/°C end-to-end, and only 5ppm/°C ratiometric, making the devices ideal for applications requiring a low-temperature-coefficient variable resistor such as low-drift, programmable-gain amplifier circuit configurations.The MAX5432/MAX5433 are available in a 3mm x 3mm 8-pin TDFN package and the MAX5434/MAX5435 are avail-able in a 6-pin thin SOT23 package. The MAX5432–MAX5435 are specified over the extended (-40°C to +85°C) temperature range.ApplicationsMechanical Potentiometer Replacement Low-Drift Programmable-Gain Amplifiers Volume ControlLiquid-Crystal Display (LCD) Screen AdjustmentFeatures♦Tiny 3mm x 3mm 8-Pin TDFN and 6-Pin Thin SOT23 Packages ♦Power-On Recall of Wiper Position from Nonvolatile Memory♦35ppm/°C End-to-End Resistance Temperature Coefficient♦5ppm/°C Ratiometric Temperature Coefficient ♦50k Ω/100k ΩResistor Values♦Fast 400kbps I 2C-Compatible Serial Interface ♦500nA (typ) Static Supply Current ♦+2.7V to +5.25V Single-Supply Operation ♦32 Tap Positions♦±0.15 LSB INL (typ), ±0.15 LSB DNL (typ)MAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometersOrdering Information19-3511; Rev 1; 12/04†Purchase of I 2C components from Maxim Integrated Products,Inc., or one of its sublicensed Associated Companies, conveys a license under the Philips I 2C Patent Rights to use these com-ponents in an I 2C system, provided that the system conforms to the I 2C Standard Specification as defined by Philips.Selector Guide appears at end of data sheet.*Future product—contact factory for availability.**EP = Exposed pad.Pin ConfigurationsM A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital PotentiometersABSOLUTE MAXIMUM RATINGSStresses 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 DD to GND...........................................................-0.3V to +6.0V SDA, SCL to GND..................................................-0.3V to +6.0V A0, H, L, and W to GND.............................-0.3V to (V DD + 0.3V)Maximum Continuous Current into H, L, and WMAX5432/MAX5434.....................................................±1.3mA MAX5433/MAX5435.....................................................±0.6mA Input/Output Latchup Immunity........................................±50mAContinuous Power Dissipation (T A = +70°C)6-Pin Thin SOT23 (derate 9.1mW/°C above +70°C)....727mW 8-Pin TDFN (derate 18.2mW/°C above +70°C)......1454.5mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature......................................................+150°C Storage Temperature Range.............................-60°C to +150°C Lead Temperature (soldering, 10s).................................+300°CELECTRICAL CHARACTERISTICSMAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometersELECTRICAL CHARACTERISTICS (continued)(V = +2.7V to +5.25V, V = V , V = GND, T = -40°C to +85°C, unless otherwise noted. Typical values are at V = +5V, T =M A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital Potentiometers TIMING CHARACTERISTICS (continued)(V DD = +2.7V to +5.25V, V H = V DD , V L = GND, T A = -40°C to +85°C, unless otherwise noted. Typical values are at V DD = +5V, T A =+25°C.) (Figures 1 and 2) (Note 1)Typical Operating Characteristics(V DD = +5V, T A = +25°C, unless otherwise noted.)00.30.90.61.21.5-4010-15356085STANDBY SUPPLY CURRENTvs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )00.20.60.40.81.02.53.53.04.04.55.05.5SUPPLY CURRENT vs. SUPPLY VOLTAGESUPPLY VOLTAGE (V)S U P P L Y C U R R E N T (µA )02135SUPPLY CURRENTvs. DIGITAL INPUT VOLTAGEDIGITAL INPUT VOLTAGE (V)S U P PL Y C U R R E N T (µA )10000.11101004Note 2:The DNL and INL are measured with the potentiometer configured as a variable resistor. For the 3-terminal potentiometers(MAX5432/MAX5433), H is unconnected and L = GND. At V DD = 5V, W is driven with a source current of 80µA for the 50k Ωconfiguration, and 40µA for the 100k Ωconfiguration. At V DD = 3V, W is driven with a source current of 40µA for the 50k Ωconfiguration, and 20µA for the 100k Ωconfiguration.Note 3:The DNL and INL are measured with the potentiometer configured as a voltage-divider with H = V DD and L = GND(MAX5432/MAX5433 only). The wiper terminal is unloaded and measured with an ideal voltmeter.Note 4:Full-scale error is defined as Note 5:Zero-scale error is defined asNote 6:The wiper resistance is the worst value measured by injecting the currents given in Note 2 into W with L = GND.R W = (V W - V H ) / I W .Note 7:The device draws current in excess of the specified supply current when the digital inputs are driven with voltages between(V DD - 0.5V) and (GND + 0.5V). See the Supply Current vs. Digital Input Voltage graph in the Typical Operating Characteristics .Note 8:Wiper is at midscale with a 10pF capacitive load. Potentiometer set to midscale, L = GND, an AC source is applied to H,and the output is measured as 3dB lower than the DC W/H value in dB.Note 9:This is measured from the STOP pulse to the time it takes the output to reach 50% of the output step size (divider mode). Itis measured with a maximum external capacitive load of 10pF.Note 10:The programming current exists only during NV writes (12ms typ).Note 11:Digital timing is guaranteed by design and characterization, and is not production tested.Note 12:An appropriate bus pullup resistance must be selected depending on board capacitance. Refer to the I 2C-bus specifica-tion document linked to this web address: /acrobat/literature/9398/39340011.pdfNote 13:The idle time begins from the initiation of the stop pulse.MAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometers1.00.5-0.5-1.0-4010-15356085END-TO-END RESISTANCE % CHANGEvs. TEMPERATURETEMPERATURE (°C)E N D -T O -E N D R E S I S T A N C E C H A N G E ( %)1.00.5-0.5-1.0-4010-15356085END-TO-END RESISTANCE % CHANGEvs. TEMPERATURETEMPERATURE (°C)E N D -T O -E N D R E S I S T A N C E % C H A N G E1µs/divTAP-TO-TAP SWITCHING TRANSIENT(0 TO MIDSCALE, C L = 10pF)V W 1V/divSDA 2V/div50k Ω1µs/divTAP-TO-TAP SWITCHING TRANSIENT(0 TO MIDSCALE, C L = 10pF)V W 1V/divSDA 2V/div100k Ω10µs/divWIPER TRANSIENT AT POWER-ONV W 1V/div V DD 2V/div50k Ω10µs/divMIDSCALE WIPER TRANSIENTAT POWER-ONV W 1V/divV DD 2V/divMAX5432–35 toc09100k ΩMIDSCALE WIPER RESPONSEvs. FREQUENCY (MAX5432)FREQUENCY (kHz)G A I N (d B )100101-15-12-9-6-30-180.11000C W = 10pFC W = 33pF-18-12-15-6-3-900.11101001000MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5433)FREQUENCY (kHz)G A I N (d B )C W = 10pFC W = 33pF100300200500600400700081241620242831WIPER RESISTANCE vs. TAP POSITION(MAX5432)M A X 5432–35 t o c 12TAP POSITIONR E S I S T A N C E (Ω)V DD = 3VTypical Operating Characteristics (continued)(V DD = +5V, T A = +25°C, unless otherwise noted.)M A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital Potentiometers Typical Operating Characteristics (continued)(V DD = +5V, T A = +25°C, unless otherwise noted.)0100300200500600400700812416202428WIPER RESISTANCE vs. TAP POSITION(MAX5433)TAP POSITIONR E S I S T A N C E (Ω)31100300200500600400700081241620242831WIPER RESISTANCE vs. TAP POSITION(MAX5432)TAP POSITIONR E S I S T A N C E (Ω)0100300200500600400700812416202428WIPER RESISTANCE vs. TAP POSITION(MAX5433)TAP POSITIONR E S I S T A N C E (Ω)31020104090301200812416202428W-TO-L RESISTANCE vs. TAP POSITIONTAP POSITION W -T O -L R E S I S T A N C E (k Ω)1101008060507031-0.5-0.3-0.4-0.1-0.20.100.20.40.30.5081241620242831RESISTANCE DNL vs. TAP POSITIONTAP POSITION R E S I S T A N C E D N L (L S B )-0.5-0.3-0.4-0.1-0.20.100.20.40.30.5081241620242831RESISTANCE INL vs. TAP POSITIONTAP POSITIONR E S I S T A N C E I N L (L S B )MAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometersTypical Operating Characteristics (continued)(V DD = +5V, T A = +25°C, unless otherwise noted.)-0.5-0.3-0.4-0.1-0.20.100.20.40.30.5081241620242831RESISTANCE DNL vs. TAP POSITIONTAP POSITION R E S I S T A N C E D N L (L S B )-0.5-0.3-0.4-0.1-0.20.100.20.40.30.5081241620242831RESISTANCE INL vs. TAP POSITIONTAP POSITION R E S I S T A N C E I N L (L S B )-0.5-0.3-0.4-0.1-0.20.100.20.40.30.50812*******28RESISTANCE DNL vs. TAP POSITIONTAP POSITIONR E S I S T A N C E D N L (L S B )31-0.5-0.3-0.4-0.1-0.20.100.20.40.30.50812416202428RESISTANCE INL vs. TAP POSITIONTAP POSITION R E S I S T A N C E I N L (L S B )31-0.5-0.3-0.4-0.1-0.20.100.20.40.30.50812416202428RESISTANCE DNL vs. TAP POSITIONTAP POSITION R E S I S T A N C E D N L (L S B )31-0.5-0.3-0.4-0.1-0.20.100.20.40.30.50812416202428RESISTANCE INL vs. TAP POSITIONTAP POSITIONR E S I S T A N C E I N L (L S B )31M A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital PotentiometersDetailed DescriptionThe MAX5432–MAX5435 contain a resistor array with 31 resistive elements. The MAX5432/MAX5434 provide a total end-to-end resistance of 50k Ω, and the MAX5433/MAX5435 provide an end-to-end resistance of 100k Ω.The MAX5432/MAX5433 allow access to the high, low,and wiper terminals for a standard voltage-divider con-figuration. Connect H, L, and W in any desired configu-ration as long as their voltages fall between GND and V DD . The MAX5434/MAX5435 are variable resistors with H internally connected to the wiper.A simple 2-wire I 2C-compatible serial interface moves the wiper among the 32 tap points. Eight data bits, an address byte, and a control byte program the wiper position. A nonvolatile memory stores and recalls the wiper position in the nonvolatile memory upon power-up.The nonvolatile memory is guaranteed for 200,000 wiper store cycles and 50 years for wiper data retention.Digital InterfaceThe MAX5432–MAX5435 feature an internal, nonvolatile EEPROM that returns the wiper to its previously stored position at power-up. The shift register decodes the control and address bits, routing the data to the proper memory registers. Write data to the volatile memory register to immediately update the wiper position, or write data to the nonvolatile register for storage. Writing to the nonvolatile register takes a minimum of 12ms.The volatile register retains data as long as the device is enabled and powered. Removing power clears the volatile register. The nonvolatile register retains data even after power is removed. Upon power-up, thepower-on reset circuitry and internal oscillator control the transfer of data from the nonvolatile register to the volatile register.Serial AddressingThe MAX5432–MAX5435 operate as a slave that sends and receives data through an I 2C- and SMBus™-com-patible 2-wire interface. The interface uses a serial data access (SDA) line and a serial clock line (SCL) to achieve bidirectional communication between master(s) and slave(s). A master, typically a microcon-troller, initiates all data transfers to and from the MAX5432–MAX5435, and generates the SCL clock that synchronizes the data transfer (Figure 1).SDA operates as both an input and an open-drain out-put. SDA requires a pullup resistor, typically 4.7k Ω.SCL only operates as an input. SCL requires a pullup resistor (4.7k Ωtyp) if there are multiple masters on the 2-wire interface, or if the master in a single-master sys-tem has an open-drain SCL output.Each transmission consists of a START (S) condition (F igure 3) sent by a master, followed by the MAX5432–MAX5435 7-bit slave address plus the 8th bit (Figure 4), 1 command byte (Figure 7) and 1 data byte,and finally a STOP (P) condition (Figure 3).Start and Stop ConditionsBoth SCL and SDA remain high when the interface is not busy. A master signals the beginning of a transmis-sion with a START (S) condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, it issues a STOP (P) condition by transitioning the SDA from low toMAX5432–MAX5435SMBus is a trademark of Intel Corporation.MAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometershigh while SCL is high. The bus is then free for another transmission (Figure 3).Bit TransferOne data bit is transferred during each clock pulse.The data on the SDA line must remain stable while SCL is high (Figure 5).AcknowledgeThe acknowledge bit is a clocked 9th bit that the recip-ient uses to handshake receipt of each byte of data (Figure 6). Each byte transferred effectively requires 9bits. The master generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, so the SDA line is stable low during the high period of the clock pulse. When the master trans-mits to the MAX5432–MAX5435, the devices generate the acknowledge bit because the MAX5432–MAX5435are the recipients.Slave AddressThe MAX5432–MAX5435 have a 7-bit-long slave address (Figure 4). The 8th bit following the 7-bit slave address is the NOP/W bit. Set the NOP/W bit low for a write command and high for a no-operation command.Table 1a shows four possible slave addresses for the MAX5432/MAX5433 and Table 1b shows four possible slave addresses for the MAX5434/MAX5435. The first 4bits (MSBs) of the slave addresses are always 0101.Bits A2 and A1 are factory programmed for the MAX5432/MAX5433 (Table 1a). Connect the A0 input (MAX5432/MAX5433 only) to either GND or V DD to select one of two I 2C device addresses. Each device must have a unique address to share the bus. A maxi-mum of four MAX5432/MAX5433 devices can share the same bus. Bits A2, A1, and A0 are factory programmed for the MAX5434/MAX5435 (Table 1b).A write to the MAX5432–MAX5435 consists of the trans-mission of the device’s slave address with the 8th bit set to zero, followed by at least 1 byte of information. The 1st byte of information is the command byte. The bytes received after the command byte are the data bytes.The 1st data byte goes into the internal register of the MAX5432–MAX5435 as selected by the command byte (Figure 8).Figure 1. I 2C Serial-Interface Timing DiagramM A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital PotentiometersCommand ByteUse the command byte to select the destination of the wiper data (nonvolatile or volatile memory registers)and swap data between nonvolatile and volatile memo-ry registers (see Table 2).Data ByteThe MAX5432–MAX5435 use the first 5 bits (MSBs,D7–D3) of the data byte to set the position of the wiper.The last 3 bits (D2, D1, and D0) are don’t care bits (see Table 2).Command DescriptionsVREG: The data byte writes to the volatile memory reg-ister and the wiper position updates with the data in the volatile memory register.NVREG: The data byte writes to the nonvolatile memory register. The wiper position is unchanged.NVREGxVREG: Data transfers from the nonvolatile memory register to the volatile memory register (wiper position updates).VREGxNVREG: Data transfers from the volatile memory register into the nonvolatile memory register.MAX5432–MAX5435Figure 2. Load Circuit Table 2. Command Byte SummaryFigure 3. Start and Stop ConditionsFigure 4. Slave AddressMAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometers______________________________________________________________________________________11Nonvolatile MemoryThe internal EEPROM consists of a 5-bit nonvolatile register that retains the value written to it before the device is powered down. The nonvolatile register is programmed with the zeros at the factory. Wait a mini-mum of 12ms after writing to NVREG before sending another command.Power-UpUpon power-up, the MAX5432–MAX5435 load the data stored in the nonvolatile memory register into the volatile memory register, updating the wiper positionwith the data stored in the nonvolatile memory register.This initialization period takes 20µs.StandbyThe MAX5432–MAX5435 feature a low-power standby mode. When the device is not being programmed, it goes into standby mode and current consumption is typically 0.5µA.Figure 5. Bit TransferFigure 6. AcknowledgeFigure 7. Command Byte ReceivedFigure 8. Command and Single Data Byte ReceivedM A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital Potentiometers12______________________________________________________________________________________Applications InformationUse the MAX5432–MAX5435 in applications requiring digitally controlled adjustable resistance, such as LCD contrast control (where voltage biasing adjusts the dis-play contrast), or for programmable filters with adjustable gain and/or cutoff frequency.Positive LCD Bias ControlF igures 9 and 10 show an application where the volt-age-divider or variable resistor is used to make an adjustable, positive LCD bias voltage. The op-amp pro-vides buffering and gain to the resistor-divider network made by the potentiometer (F igure 9) or to a fixed resistor and a variable resistor (Figure 10).Programmable FilterF igure 11 shows the configuration for a 1st-order pro-grammable filter. The gain of the filter is adjusted byR2, and the cutoff frequency is adjusted by R3. Use the following equations to calculate the gain (G) and the 3dB cutoff frequency (f C ).Adjustable Voltage ReferenceF igure 12 shows the MAX5432/MAX5433 used as the feedback resistors in an adjustable voltage reference application. Independently adjust the output voltages of the MAX6160 from 1.23V to (V IN - 0.2V) by changingthe wiper position of the MAX5432/MAX5433.MAX5432–MAX5435Figure 11. Programmable FilterMAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometers______________________________________________________________________________________13MAX5432/MAX5433 Functional DiagramMAX5434/MAX5435 Functional DiagramM A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital Potentiometers 14______________________________________________________________________________________MAX5432–MAX5435Selector GuideChip InformationTRANSISTOR COUNT: 7817PROCESS: BiCMOSMAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometersPackage Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to /packages .)M A X 5432–M A X 543532-Tap, Nonvolatile, I 2C, Linear, Digital Potentiometers 16______________________________________________________________________________________MAX5432–MAX5435Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to /packages.)MAX5432–MAX543532-Tap, Nonvolatile, I 2C, Linear, DigitalPotentiometersMaxim 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.Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________17©2004 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to /packages.)。

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6通道智能风扇控制器MAX3178519-5703; Rev 0; 12/10+表示无铅(Pb)/符合RoHS 标准的封装。

T = 卷带包装。

*EP = 裸焊盘。

概述MAX31785是一款闭环多通道风扇控制器。

自动闭环风扇控制架构将风扇控制在尽可能低的转速，从而节省系统功率。

低风扇转速的其它优势包括：有效降低可闻噪声和更长的风扇寿命、更少的系统维护。

根据用户可编程查找表(LUT)，器件根据11个温度传感器中的一个或多个传感器测量值，自动调节6个独立风扇的转速。

也可以由外部主机手动控制风扇转速，器件自动调整风扇转速。

器件具有风扇状况诊断功能，帮助用户预防将要发生的风扇故障。

器件还可监测多达6路远端电压。

应用网络交换机/路由器基站服务器智能电网系统工业控制定购信息特性S 6路独立的风扇控制通道 支持3线和4线风扇 自动闭环风扇转速控制 基于RPM 或PWM 控制 可选手动控制模式快速、慢速PWM 频率选项 风扇交替启动，缓解电源压力 双转速计(支持12个风扇) 风扇故障检测 风扇运转状态监测 非易失风扇运转时间表S 支持多达11个温度传感器6个外部温度二极管，带有串联电阻自动抵消功能 1个内部温度传感器 4个I 2C 数字温度传感器对所有温度传感器进行故障检测S 6路ADC 测量远端电压S PMBus™兼容命令接口S I 2C/SMBus™兼容串行总线，带有总线超时功能S 板载非易失故障记录和默认配置设置S 无需外部时钟S +3.3V 供电PMBus 是SMIF, Inc.的商标。