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RT2101A®DS2101A-08 May 2022Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.©Design Tools Sample &BuyReference Design General DescriptionThe RT2101A is a high efficiency step-down converter and capable of delivering 3A output current over a wide input voltage range from 2.95V to 6V.The RT2101A provides accurate regulation for a variety of loads with ±2.5% accuracy. For reducing inductor size, it provides up to 2MHz switching frequency. The efficiency is maximized through the integrated 45m Ω MOSFETs and 550μA typical supply current.Under-voltage lockout voltage of the RT2101A is 2.7V , and it also provides external setting by a resistor network on the enable pin.The RT2101A provides protections such as inductor current limit under-voltage lockout and thermal shutdown.The over-temperature threshold is 145°C.The RT2101A is available in WQFN-16L 3x3 package.2.95V to 6V Input, 3A Output, 2MHz, Synchronous Step-Down ConverterFeatures●AEC-Q100 Grade 2 Qualified ●Integrated 45m Ω MOSFETs ●Input Range : 2.95V to 6V●Adjustable PWM Frequency : 700kHz to 2MHz ●Output Current : 3A ●95% Efficiency●Adjustable Soft-Start ●Power Good Indicator ●Enable Control●Under-Voltage Lockout ●Current Limit ●Thermal ShutdownApplications●Low-Voltage, High-Density Power Systems ●Distributed Power Systems ●Point-of-Load ConversionsSimplified Application CircuitVOUTMarking Information72= : Product CodeYMDNN : Date CodeOrdering InformationNote :Richtek products are :❝ RoHS compliant and compatible with the current require-ments of IPC/JEDEC J-STD-020.❝ Suitable for use in SnPb or Pb-free soldering processes.RT2101AG : Green (Halogen Free and Pb Free)RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Functional Block DiagramPin Configuration(TOP VIEW)WQFN-16L 3x3GNDGND VIN VIN SW SW SS/TRSW A G N D C O M P F B R T /S Y N CI N N O O TG O O DDS2101A-08 May 2022RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.OperationThe RT2101A is a synchronous step-down DC-DC converter with two integrated power MOSFETs. It can deliver up to 3A output current from a 2.95V to 6V input supply. The RT2101A's current mode architecture allows the transient response to be optimized over a wider input voltage and load range. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The RT2101A is synchronizable to an external clock with frequency ranging from 700kHz to 2MHz. The RT2101A is available in WQFN-16L 3x3 package.High-side MOSFET peak current is measured by internal sensing resistor. The Current Signal is where Slope Compensator works together with sensing voltage sensing resistor. The error amplifier adjusts COMP voltage by comparing the feedback signal (V FB ) from the output voltage with the internal 0.827V reference. When the load current increases, it causes a drop in the feedback voltage relative to the reference, the COMP voltage then rises to allow higher inductor current to match the load current.EN ComparatorThe RT2101A is enable when EN pin is higher than 1.25V.It is disable when EN pin lower than 1.18V. There is an internal pull-high current source to charge the EN pin to high when the EN pin is floating.Oscillator (OSC)The internal oscillator that provides switching frequency from 700kHz to 2MHz. It is adjusted using an external timing resistor. It also can be synchronized by an external clock in the range between 700kHz and 2MHz from RT/SYNC pin.PGOOD ComparatorWhen the feedback voltage (V FB ) rises above 93% or falls below 107% of reference voltage the PGOOD open drain output will be high impedance. The PGOOD open drain output will be internally pulled low when the feedback voltage (V FB ) falls below 88% or rises above 113% of reference voltage.Soft-Start (SS)An internal current source (2.2μA) charges an external capacitor to build the soft-start ramp voltage (V SS ). The V FB voltage will track the V SS during soft-start interval.The Soft-Start setting capacitor (C SS ) for the Soft-Start time (t SS ) can be easily calculated by the following equation :Over-Temperature Protection (OTP)The RT2101A implement an internal over-temperature protection. When junction temperature is higher than 145°C, it will stop switching. Until the junction temperature decreases below 125°C, the RT2101A will re-soft-start from initial condition.SS SS t (ms) 2.2 (A)C (nF) =0.827 (V)⨯μRT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Electrical Characteristics(V IN= 5V, C IN = 10μF, T A = T J = −40°C to 105°C, unless otherwise specified)Absolute Maximum Ratings (Note 1)●Supply Input Voltage, VIN ----------------------------------------------------------------------------------------- −0.3V to 7V●Switch Node Voltage, SW ----------------------------------------------------------------------------------------- −1V to (V IN + 0.3V)<100ns ----------------------------------------------------------------------------------------------------------------- −5V to (V IN + 5V)●BOOT to SW --------------------------------------------------------------------------------------------------------- −0.3V to 7V●Other Pins------------------------------------------------------------------------------------------------------------- −0.3V to (V IN + 0.3V)●Power Dissipation, P D @ T A = 25°CWQFN-16L 3x3------------------------------------------------------------------------------------------------------3.33W●Package Thermal Resistance (Note 2)WQFN-16L 3x3, θJA -------------------------------------------------------------------------------------------------30°C/W WQFN-16L 3x3, θJC ------------------------------------------------------------------------------------------------7.5°C/W ●Junction T emperature -----------------------------------------------------------------------------------------------150°C ●Lead Temperature (Soldering, 10 sec.)-------------------------------------------------------------------------260°C●Storage T emperature Range -------------------------------------------------------------------------------------- −65°C to 150°C ●ESD Susceptibility (Note 3)HBM (Human Body Model)----------------------------------------------------------------------------------------2kVRecommended Operating Conditions (Note 4)●Supply Input Voltage ------------------------------------------------------------------------------------------------2.95V to 6V ●Junction T emperature Range -------------------------------------------------------------------------------------- −40°C to 125°C ●Ambient T emperature Range -------------------------------------------------------------------------------------- −40°C t o 105°CDS2101A-08 May 2022RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Note 1. Stresses beyond those listed “Absolute Maximum Ratings ” may cause permanent damage to the device. These arestress 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 may affect device reliability.Note 2. θJA is measured at T A = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC ismeasured at the exposed pad of the package.Note 3. Devices are ESD sensitive. Handling precautions are recommended.Note 4. The device is not guaranteed to function outside its operating conditions.Note 5. Guarantee by Design .RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Typical Application CircuitTable 1. Recommended Component SelectionV V OUT 1.8VDS2101A-08 May 2022RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Typical Operating CharacteristicsReference Voltage vs. Temperature0.800.810.820.830.840.85-50-25255075100125Temperature (°C)R e f e r e n c e V o l t a g e (V )Frequency vs. Temperature9009209409609801000-50-25255075100125Temperature (°C)F r e q u e n c y (k H z )Frequency vs. Input Voltage0.920.930.940.950.960.970.980.991.001.011.0233.544.555.56Input Voltage (V)F r e q u e n c y (M H z )Efficiency vs. Output Current1020304050607080901000.0010.010.1110Output Current (A)E f f i c i e n c y (%)Efficiency vs. Output Current1020304050607080901000.0010.010.1110Output Current (A)E f f i c i e n c y (%)Output Voltage vs. Output Current1.801.811.821.831.841.850.511.522.53Output Current (A)O u t p u t V o l t a g e (V)RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Output Ripple Time (500ns/Div)I L (1A/Div)V OUT (10mV/Div)V SW(5V/Div)V IN = 3.3V, V OUT = 1.8V, I OUT = 1ACurrent Limit vs. Temperature6.06.67.27.88.49.0-50-25255075100125Temperature (°C)C u r r e n t L i m i t (A )Current Limit vs. Input Voltage6.06.57.07.58.08.59.033.544.555.56Input Voltage (V)C u r r e n t L i m i t(A )Output RippleTime (500ns/Div)I L (2A/Div)V OUT (10mV/Div)V SW (5V/Div)V IN = 3.3V, V OUT = 1.8V, I OUT = 3AUVLO vs. Temperature2.32.42.52.62.72.82.9-50-25255075100125Temperature (°C)U V L O (V)Enable Threshold Voltage vs. Temperature1.001.081.161.241.321.40-50-25255075100125Temperature (°C)E n a b l e T h r e s h o l d V o l t a g e (V )DS2101A-08 May 2022RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Load Transient ResponseI OUT (1A/Div)V OUT(200mV/Div)V IN = 3.3V, V OUT = 1.8V, I OUT = 0A to 3ATime (100μs/Div)Switching Frequency vs. R RT3004005006007008009001000R RT (k )S w i t c h i n g F r e q u e n c y (k H z )ΩSwitching Frequency vs. R RT6080100120140160180200R RT (k )S w i t c h i n g F r e q u e n c y (k H z )ΩLoad Transient ResponseTime (100μs/Div)I OUT (1A/Div)V OUT(200mV/Div)V IN = 5V, V OUT = 3.3V, I OUT = 0A to 3ART2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Application InformationThe basic RT2101A application circuit is shown in Typical Application Circuit. External component selection is determined by the maximum load current and begins with the selection of the inductor value and operating frequency followed by C IN and C OUT . The switching frequency range from 700kHz to 2MHz. It is adjusted by using a resistor to ground on the RT/SYNC pin.Output Voltage SettingThe resistive divider allows the FB pin to sense the output voltage as shown in Figure 1.Figure 1. Setting the Output VoltageThe output voltage setting range is 0.827V to 3.6V and the set by an external resistive divider is according to the following equation :⎛⎫+ ⎪⎝⎭OUT FB R1V = V 1R2where V FB is the feedback reference voltage 0.827V (typ.).Inductor SelectionFor a given input and output voltage, the inductor value and operating frequency determine the ripple current. The ripple current ΔI L increases with higher V IN and decreases with higher inductance :⎡⎤⎡⎤∆⨯-⎢⎥⎢⎥⨯⎣⎦⎣⎦OUT OUT L OSC IN V V I =1f L V Having a lower ripple current reduces the ESR losses in the output capacitors and the output voltage ripple. Highest efficiency operation is achieved at low frequency with small ripple current. This, however, requires a large inductor. A reasonable starting point for selecting the ripple current is ΔI L = 0.4 (IMAX). The largest ripple current occurs at the highest V IN . To guarantee that the ripple current stays below a specified maximum, the inductor value should be chosen according to the following equation :⎡⎤⎡⎤⨯-⎢⎥⎢⎥⨯∆⎣⎦⎣⎦OUT OUT OSC L(MAX)IN(MAX)V V L =1f I V Input and Output Capacitors SelectionThe input capacitance, C IN , is needed to filter the trapezoidal current at the source of the top MOSFET. A low ESR input capacitor with larger ripple current rating should be used for the maximum RMS current. RMScurrent is given by :RMS OUT(MAX)I = I This formula has a maximum at V IN = 2V OUT , where I RMS =I OUT / 2. This simple worst case condition is commonly used for design because even significant deviations do not offer much relief. Note that ripple current ratings from capacitor manufacturers are often based on only 2000hours of life, which makes it advisable to either further derate the capacitor or choose a capacitor rated at a higher temperature than required. Several capacitors may also be placed in parallel to meet size or height requirements in the design. The selection of C OUT is determined by the effective series resistance (ESR) that is required to minimize voltage ripple, load step transients, and the amount of bulk capacitance that is necessary to ensure that the control loop is stable. Loop stability can be examined by viewing the load transient response as described in a later section. The output ripple, ΔV OUT , is determined by :⎡⎤∆≤∆+⎢⎥⎣⎦OUT L OSC OUT 1V I ESR 8f C Using Ceramic Input and Output CapacitorsHigher values, lower cost ceramic capacitors are nowbecoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. However, care must be taken when these capacitors are used at the input and output. When a ceramic capacitor is used at the input and the power is supplied by a wall adapter through long wires, a load step at the output can induce ringing at the input, V IN . At best, this ringing can couple with the output and be mistaken as loop instability. At worst, a sudden inrush of current through the long wires can potentially cause a voltage spike at V IN large enough to damage the part.V OUT11DS2101A-08 May 2022RT2101A©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.Thermal ConsiderationsFor continuous operation, do not exceed absolutemaximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula :P D(MAX) = (T J(MAX) − T A ) / θJAwhere T J(MAX) is the maximum junction temperature, T A is the ambient temperature, and θJA is the junction to ambient thermal resistance.For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA , is layout dependent. For WQFN-16L 3x3 package, the thermal resistance, θJA , is 30°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at T A = 25°C can be calculated by the following formula :P D(MAX) = (125°C − 25°C) / (30°C/W) = 3.33W for WQFN-16L 3x3 packageThe maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA . The derating curve in Figure 2 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation.Figure 2. Derating Curve of Maximum Power DissipationLayout ConsiderationsFor the best performance of the RT2101A, the following guidelines must be strictly followed.❝The input capacitor should be placed as close as possible to the device pins (VIN and GND).❝The RT/SYNC pin is sensitive. The RT resistor should be located as close as possible to the IC and minimal lengths of trace.❝The SW node is with high frequency voltage swing. It should be kept at a small area.❝Place the feedback components as close as possible to the IC and keep away from the noisy devices.❝The GND and AGND should be connected to a strong ground plane for heat sinking and noise protection.0.00.40.81.21.62.02.42.83.23.60255075100125Ambient Temperature (°C)M a x i m u m P o w e r D i s s i p a t i o n (W )©Copyright 2022 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.12DS2101A-08 May 2022 RT2101AFigure 3. PCB Layout GuideW-Type 16L QFN 3x3 PackageRichtek Technology Corporation14F, No. 8, Tai Yuen 1st Street, Chupei CityHsinchu, Taiwan, R.O.C.Tel: (8863)5526789Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.DS2101A-08 May 13。
General DescriptionThe MAX5094A/B/C/D/MAX5095A/B/C BiCMOS, high-performance, current-mode PWM controllers have all the features required for wide input-voltage range isolated/nonisolated power supplies. These controllers are used for low- and high-power universal input volt-age and telecom power supplies.The MAX5094/MAX5095 contain a fast comparator with only 60ns typical delay from current sense to the output for overcurrent protection. The MAX5094 has an inte-grated error amplifier with the output at COMP. Soft-start is achieved by controlling the COMP voltage rise using external components.The oscillator frequency is adjustable from 20kH z to 1MHz with an external resistor and capacitor. The tim-ing capacitor discharge current is trimmed allowing for programmable dead time and maximum duty cycle for a given frequency. The available saw-toothed waveform at R T C T can be used for slope compensation when needed.The MAX5095A/MAX5095B include a bidirectional syn-chronization circuit allowing for multiple controllers to run at the same frequency to avoid beat frequencies.Synchronization is accomplished by simply connecting the SYNC of all devices together. When synchronizing with other devices, the MAX5095A/MAX5095B with the highest frequency synchronizes the other devices.Alternatively, the MAX5095A/MAX5095B can be syn-chronized to an external clock with an open-drain out-put stage running at a higher frequency.The MAX5095C provides a clock output pulse (ADV_CLK) that leads the driver output (OUT) by 110ns. The advanced clock signal is used to drive the secondary-side synchronous rectifiers.The MAX5094A/B/C are available in the 8-pin SO and 8-pin µMAX ®packages. The MAX5094D and MAX5095A/B/C are available in the 8-pin µMAX pack-age. All devices operate over the automotive tempera-ture range of -40°C to +125°C.ApplicationsUniversal Input AC/DC Power Supplies Isolated Telecom Power Supplies Isolated Power-Supply Modules Networking SystemsComputer Systems/Servers Industrial Power Conversion Isolated Keep-Alive CircuitsFeatures♦Pin-for-Pin Replacement for UCC28C43(MAX5094A) and UCC28C45 (MAX5094B)♦2A Drive Source and 1A Sink Capability ♦Up to 1MHz Switching Frequency Operation ♦Bidirectional Frequency Synchronization (MAX5095A/MAX5095B)♦Advanced Output Drive for Secondary-Side Synchronous Rectification (MAX5095C)♦Fast 60ns Cycle-by-Cycle Current Limit♦Trimmed Oscillator Capacitor Discharge Current Sets Maximum Duty Cycle Accurately ♦Accurate ±5% Start Voltage with 0.8V Hysteresis ♦Low 32µA Startup Current♦5V Regulator Output (REF) with 20mA Capability ♦Versions with 0.3V Current-Sense Threshold ♦Overtemperature ShutdownMAX5094A/B/C/D/MAX5095A/B/CHigh-Performance, Single-Ended, Current-ModePWM Controllers________________________________________________________________Maxim Integrated Products119-3864; Rev 3; 10/06For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .µMAX is a registered trademark of Maxim Integrated Products, Inc.M A X 5094A /B /C /D /M A X 5095A /B /CPWM ControllersABSOLUTE MAXIMUM RATINGSELECTRICAL CHARACTERISTICSStresses 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 (Low-Impedance Source) to GND..................-0.3V to +30V V CC (I CC < 30mA).....................................................Self Limiting OUT to GND...............................................-0.3V to (V CC + 0.3V)OUT Current.............................................................±1A for 10µs FB, SYNC, COMP, CS, R T /C T , REF to GND.............-0.3V to +6V COMP Sink Current (MAX5094)..........................................10mAContinuous Power Dissipation (T A = +70°C)8-Pin µMAX (derate 4.5mW/°C above +70°C).............362mW 8-Pin SO (derate 5.9mW/°C above +70°C)...............470.6mW Operating Temperature Range .........................-40°C to +125°C Maximum Junction Temperature.....................................+150°C Storage Temperature Range.............................-65°C to +150°C Lead Temperature (soldering, 10s).................................+300°CELECTRICAL CHARACTERISTICS (continued)MAX5094A/B/C/D/MAX5095A/B/C PWM Controllers(V= +15V, R= 10kΩ, C= 3.3nF, REF = open, C= 0.1µF, COMP = open, V= 2V, CS = GND, T= T= -40°C to +85°C,M A X 5094A /B /C /D /M A X 5095A /B /CPWM ControllersELECTRICAL CHARACTERISTICS (continued)(V CC = +15V, R T = 10k Ω, C T = 3.3nF, REF = open, C REF = 0.1µF, COMP = open, V FB = 2V, CS = GND, T A = T J = -40°C to +85°C ,unless otherwise noted.) (Note 1)ELECTRICAL CHARACTERISTICS(V = +15V, R = 10k Ω, C = 3.3nF, REF = open, C = 0.1µF, COMP = open, V = 2V, CS = GND, T = T = -40°C to +125°C ,ELECTRICAL CHARACTERISTICS (continued)MAX5094A/B/C/D/MAX5095A/B/C PWM Controllers(V= +15V, R= 10kΩ, C= 3.3nF, REF = open, C= 0.1µF, COMP = open, V= 2V, CS = GND, T= T= -40°C to +125°C,M A X 5094A /B /C /D /M A X 5095A /B /CPWM Controllers 6_______________________________________________________________________________________ELECTRICAL CHARACTERISTICS (continued)Note 1:All devices are 100% tested at +25°C. All limits over temperature are guaranteed by design, not production tested.Note 2:Guaranteed by design, not production tested.Note 3:Parameter measured at trip point of latch with V FB = 0 (MAX5094 only).Note 4:Gain is defined as A = ∆V COMP / ∆V CS , 0 ≤V CS ≤0.8V for MAX5094A/MAX5094B, 0 ≤V CS ≤0.2V for MAX5094C/MAX5094D/ MAX5095_.Note 5:Output frequency equals oscillator frequency for MAX5094A/MAX5094C/MAX5095A. Output frequency is one-half oscillatorfrequency for MAX5094B/MAX5094D/MAX5095B/MAX5095C.Typical Operating Characteristics(V CC = 15V, T A = +25°C, unless otherwise noted.)BOOTSTRAP UVLO vs. TEMPERATURETEMPERATURE (°C)V C C (V )110956580-105203550-25012345678910-40125252739312933353741-40-10520-253550958011065125STARTUP CURRENT vs. TEMPERATURETEMPERATURE (°C)I C C (µA )3.53.74.94.13.94.34.54.75.1OPERATING SUPPLY CURRENT vs. TEMPERATURE AFTER STARTUP(f OSC = f SW = 300kHz)I C C (m A )-40-10520-253550958011065125TEMPERATURE (°C)MAX5094A/B/C/D/MAX5095A/B/CPWM Controllers_______________________________________________________________________________________7Typical Operating Characteristics (continued)(V CC = 15V, T A = +25°C, unless otherwise noted.)4.904.944.925.004.984.965.025.045.065.08REFERENCE VOLTAGE vs. TEMPERATUREV R E F (V )-40-10520-253550958011065125TEMPERATURE (°C)4.654.754.704.854.805.004.954.905.05020103040506070REFERENCE VOLTAGE vs. REFERENCE LOAD CURRENTM A X 5094/95 t o c 05I REF (mA)V R E F (V ) 4.9804.9844.9824.9884.9864.9924.9904.9944.9984.9965.000101416121820222426REFERENCE VOLTAGE vs. SUPPLY VOLTAGEV CC (V)V R E F (V )450470460500490480510520540530550-40-105-25203550658095110125OSCILLATOR FREQUENCY (f OSC )vs. TEMPERATURETEMPERATURE (°C)O S C I L L A T O R F R E Q U E N C Y (k H z )7.887.908.027.947.927.967.988.008.04-40-10520-253550958011065125OSCILLATOR R T /C TDISCHARGE CURRENTvs. TEMPERATURETEMPERATURE (°C)R T /C T D I S C H A R G E C U R R E N T (m A )201050403060709080100MAXIMUM DUTY CYCLE vs. TEMPERATURED U T Y C Y C LE (%)-40-10520-253550958011065125TEMPERATURE (°C)1000150050020002500300035004000MAXIMUM DUTY CYCLE vs. FREQUENCY MAX5094A/MAX5094C/MAX5095AOSCILLATOR FREQUENCY (kHz)0201050403060709080100D U T Y C Y C L E (%)0.900.940.921.000.980.961.021.041.081.061.10CURRENT-SENSE TRIP THRESHOLDvs. TEMPERATUREC S T H R E S H O LD (V )-40-10520-253550958011065125TEMPERATURE (°C)0.200.240.220.300.280.260.320.340.380.360.40CURRENT-SENSE TRIP THRESHOLDvs. TEMPERATUREC S T H R E S H O LD (V )-40-10520-253550958011065125TEMPERATURE (°C)M A X 5094A /B /C /D /M A X 5095A /B /CPWM Controllers 8_______________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 15V, T A = +25°C, unless otherwise noted.)TIMING RESISTANCE vs. OSCILLATOR FREQUENCYFREQUENCY (Hz)R T (k Ω)1,000,000100,00011010010000.110,00010,000,000OUT IMPEDANCE vs. TEMPERATURE(R DS_ON PMOS DRIVER)TEMPERATURE (°C)R D S _O N (Ω)110956580-105203550-252.22.42.62.83.03.23.43.63.84.04.24.44.64.85.02.0-4012521543679810OUT IMPEDANCE vs. TEMPERATURE(R DS_ON NMOS DRIVER)R D S _O N (Ω)-40-10520-253550958011065125TEMPERATURE (°C)201050403060709080100PROPAGATION DELAY FROM CURRENT-LIMIT COMPARATOR TO OUT vs. TEMPERATUREM A X 5094/95 t o c 15P R O P A G A T I O N D E L A Y (n s )-40-10520-253550958011065125TEMPERATURE (°C)ERROR-AMPLIFIER OPEN-LOOP GAINAND PHASE vs. FREQUENCYFREQUENCY (Hz)G A I N (d B )1M 100k 1k 10k 10100120406080100120140-200.01100M10M -165-140-115-90-65-40-1510-190P H A S E (D E G R E E S )1.51.62.21.81.71.92.02.12.3-40-10520-253550958011065125COMP VOLTAGE LEVEL TO TURN OFF DEVICE vs. TEMPERATURETEMPERATURE (°C)V C O M P (V )100104102110108106112114118116120ADV_CLK RISING EDGE TO OUT RISINGEDGE TIME vs. TEMPERATURET I M E (n s )-40-10520-253550958011065125TEMPERATURE (°C)t = 20ns/divADV_CLK AND OUT WAVEFORMSOUT 10V/divADV_CLK 5V/divLOAD = 4.75k ΩV CC = 15V MAX5095CMAX5094A/B/C/D/MAX5095A/B/CPWM Controllers_______________________________________________________________________________________9Typical Operating Characteristics (continued)(V CC = 15V, T A = +25°C, unless otherwise noted.)Pin Descriptionst = 400ns/divOUT SOURCE AND SINK CURRENTSI OUT 4A/divV OUT 10V/divV CC = 15VC OUT = 10nF2.03.02.54.03.55.04.55.56.56.07.0202203204201205206207209208201020SUPPLY CURRENTvs. OSCILLATOR FREQUENCYFREQUENCY (kHz)I C C (m A )MAXIMUM DUTY CYCLE vs. R T MAX5094A/MAX5095AR T (Ω)D U T Y C Y C LE (%)10,00010003040506070809010020100100,000M A X 5094A /B /C /D /M A X 5095A /B /CPWM Controllers 10______________________________________________________________________________________Pin Descriptions (continued)Detailed Description The MAX5094_/MAX5095_ current-mode PWM con-trollers are designed for use as the control and regulation core of flyback or forward topology switching power sup-plies. These devices incorporate an integrated low-side driver, adjustable oscillator, error amplifier (MAX5094_ only), current-sense amplifier, 5V reference, and external synchronization capability (MAX5095A/MAX5095B only). An internal +26.5V current-limited V CC clamp prevents overvoltage during startup.Eight different versions of the MAX5094/MAX5095 are available as shown in the Selector Guide. The MAX5094A/MAX5094B are the standard versions with a feedback input (FB) and internal error amplifier. The MAX5095A/MAX5095B include bidirectional synchroniza-tion (SYNC). This enables multiple MAX5095A/ MAX5095Bs to be connected and synchronized to the device with the highest frequency. The MAX5095C includes an ADV_CLK output, which precedes the MAX5095C’s drive output (OUT) by 110ns. Figures 1, 2, and 3 show the internal functional diagrams of the MAX5094_, MAX5095A/MAX5095B, and MAX5095C, respectively. The MAX5094A/MAX5094C/MAX5095A are capable of 100% maximum duty cycle. The MAX5094B/ MAX5094D/MAX5095B/MAX5095C limit the maximum duty cycle to 50%. MAX5094A/B/C/D/MAX5095A/B/C PWM ControllersFigure 1. MAX5094_ Functional DiagramM A X 5094A /B /C /D /M A X 5095A /B /CCurrent-Mode Control LoopThe advantages of current-mode control over voltage-mode control are twofold. First, there is the feed-forward characteristic brought on by the controller’s ability to adjust for variations in the input voltage on a cycle-by-cycle basis. Secondly, the stability requirements of the current-mode controller are reduced to that of a single-pole system unlike the double pole in the voltage-mode control scheme.The MAX5094/MAX5095 use a current-mode control loop where the output of the error amplifier is compared to the current-sense voltage (V CS ). When the current-sense sig-nal is lower than the inverting input of the CPWM com-parator, the output of the comparator is low and the switch is turned on at each clock pulse. When the cur-rent-sense signal is higher than the inverting input of the CPWM comparator, the output is high and the switch is turned off.PWM ControllersFigure 2. MAX5095A/B Functional DiagramV CC and Startup In normal operation, V CC is derived from a tertiary wind-ing of the transformer. H owever, at startup there is no energy delivered through the transformer, thus a resistor must be connected from V CC to the input power source (see R ST and C ST in Figures 5 to 8). During startup, C ST charges up through R ST. The 5V reference generator, comparator, error amplifier, oscillator, and drive circuit remain off during UVLO to reduce startup current below 65µA. When V CC reaches the undervoltage-lockout threshold of 8.4V, the output driver begins to switch and the tertiary winding supplies power to V CC. V CC has an internal 26.5V current-limited clamp at its input to protect the device from overvoltage during startup.Size the startup resistor, R ST, to supply both the maxi-mum startup bias (I START) of the device (65µA max) and the charging current for C ST. The startup capacitor C ST must charge to 8.4V within the desired time period t ST(for example, 500ms). The size of the startup capacitor depends on:1)IC operating supply current at a programmed oscilla-tor frequency (f OSC).2)The time required for the bias voltage, derived froma bias winding, to go from 0 to 9V.3)The MOSFET total gate charge.4)The operating frequency of the converter (f SW). MAX5094A/B/C/D/MAX5095A/B/C PWM ControllersFigure 3. MAX5095C Functional DiagramM A X 5094A /B /C /D /M A X 5095A /B /CTo calculate the capacitance required, use the following formula:where:I G = Q G f SWI CC is the MAX5094/MAX5095s’ maximum internal sup-ply current after startup (see the Typical Operating Characteristics to find the I IN at a given f OSC ). Q G is the total gate charge for the MOSFET, f SW is the converter switching frequency, V HYST is the bootstrap UVLO hys-teresis (0.8V), and t SS is the soft-start time, which is set by external circuitry.Size the resistor R ST according to the desired startup time period, t ST , for the calculated C ST . Use the follow-ing equations to calculate the average charging current (I CST ) and the startup resistor (R ST ):Where V INMIN is the minimum input supply voltage for the application (36V for telecom), V SUVR is the bootstrap UVLO wake-up level (8.4V), and I START is the V IN supply current at startup (65µA, max). Choose a higher value for R ST than the one calculated above if longer startup times can be tolerated to minimize power loss in R ST .The equation for C ST above gives a good approximation of C ST , yet neglects the current through R ST . Fine tuneThe above startup method is applicable to circuits wherethe tertiary winding has the same phase as the output windings. Thus, the voltage on the tertiary winding at any given time is proportional to the output voltage and goes through the same soft-start period as the output voltage.The minimum discharge time of C ST from 8.4V to 7.6V must be greater than the soft-start time (t SS ).Undervoltage Lockout (UVLO)The minimum turn-on supply voltage for the MAX5094/MAX5095 is 8.4V. Once V CC reaches 8.4V,the reference powers up. There is 0.8V of hysteresis from the minimum turn-on voltage to the UVLO thresh-old. Once V CC reaches 8.4V, the MAX5094/MAX5095operates with V CC down to 7.6V. Once V CC goes below 7.6V the device is in UVLO. When in UVLO, the quies-cent supply current into V CC falls back to 32µA (typ),and OUT and REF are pulled low.MOSFET DriverOUT drives an external n-channel MOSFET and swings from GND to V CC . Ensure that V CC remains below the absolute maximum V GS rating of the external MOSFET.OUT is a push-pull output with the on-resistance of the PMOS typically 3.5Ωand the on-resistance of the NMOS typically 4.5Ω. The driver can source 2A typically and sink 1A typically. This allows for the MAX5094/MAX5095to quickly turn on and off high gate-charge MOSFETs.Bypass V CC with one or more 0.1µF ceramic capacitors to GND, placed close to the MAX5094/MAX5095. The average current sourced to drive the external MOSFET depends on the total gate charge (Q G ) and operating frequency of the converter. The power dissipation in the MAX5094/MAX5095 is a function of the average output-drive current (I DRIVE ). Use the following equation to cal-culate the power dissipation in the device due to IDRIVE :I DRIVE = Q G x f SWPD = (I DRIVE + I CC) x V CC where, I CC is the operating supply current. See the Typical Operating Characteristics for the operating supply current at a given frequency.Error Amplifier (MAX5094)The MAX5094 includes an internal error amplifier. The inverting input is at FB and the noninverting input is inter-nally connected to a 2.5V reference. The internal error amplifier is useful for nonisolated converter design (see Figure 6) and isolated design with primary-side regulation through a bias winding (see Figure 5). In the case of a nonisolated power supply, the output voltage is:where, R1 and R2 are from Figure 6.PWM ControllersMAX5095_FeedbackThe MAX5095A/MAX5095B/MAX5095C use either an external error amplifier when designed into a nonisolat-ed converter or an error amplifier and optocoupler when designed into an isolated power supply. The COMP input is level-shifted and connected to the inverting terminal of the PWM comparator (CPWM).Connect the COMP input to the output of the external error amplifier for nonisolated design. Pull COMP high externally to 5V (or REF) and connect the optocoupler transistor as shown in Figures 7 and 8. COMP can be used for soft-start and also as a shutdown. See the Typical Operating Characteristics to find the turn-off COMP voltage at different temperatures.OscillatorThe oscillator frequency is programmed by adding an external capacitor and resistor at R T /C T (see R T and C T in the Typical Application Circuits ). R T is connected from R T /C T to the 5V reference (REF) and C T is con-nected from R T /C T to GND. REF charges C T through R T until its voltage reaches 2.8V. C T then discharges through an 8.3mA internal current sink until C T ’s voltage reaches 1.1V, at which time C T is allowed to charge through R T again. The oscillator’s period will be the sum of the charge and discharge times of C T . Calculate the charge time ast C = 0.57 x R T x C TThe discharge time is thenThe oscillator frequency will then beFor the MAX5094A/MAX5094C/MAX5095A, the convert-er output switching frequency (f SW ) is the same as the oscillator frequency (f OSC ). For the MAX5094B/MAX5094D/MAX5095B/MAX5095C, the output switch-ing frequency is 1/2 the oscillator frequency.Reference OutputREF is a 5V reference output that can source 20mA.Bypass REF to GND with a 0.1µF capacitor.Current LimitThe MAX5094/MAX5095 include a fast current-limit com-parator to terminate the ON cycle during an overload or a fault condition. The current-sense resistor (R CS ), connect-ed between the source of the MOSFET and GND, sets the current limit. The CS input has a voltage trip level (V CS ) of 1V (MAX5094A/B) or 0.3V (MAX5094C/D,MAX5095_). Use the following equation to calculate R CS :I P-P is the peak current in the primary that flows through the MOSFET. When the voltage produced by this current (through the current-sense resistor) exceeds the current-limit comparator threshold, the MOSFET driver (OUT) will turn the switch off within 60ns. In most cases, a small RC filter is required to filter out the leading-edge spike on the sense waveform. Set the time constant of the RC filter at 50ns. Use a current transformer to limit the losses in the current-sense resistor and achieve higher efficiency especially at low input-voltage operation.Synchronization (MAX5095A/MAX5095B)SYNCSYNC is a bidirectional input/output that outputs a syn-chronizing pulse and accepts a synchronizing pulse from other MAX5095A/MAX5095Bs (see Figures 7 and 9). As an output, SYNC is an open-drain p-channel MOSFET driven from the internal oscillator and requires an external pulldown resistor (R SYNC ) between 500Ωand 5k Ω. As an input, SYNC accepts the output pulses from other MAX5095A/MAX5095Bs.Synchronize multiple MAX5095A/MAX5095Bs by con-necting their SYNC pins together. All devices connected together will synchronize to the one operating at the highest frequency. The rising edge of SYNC will precede the rising edge of OUT by approximately the discharge time (t D ) of the oscillator (see the Oscillator section). The pulse width of the SYNC output is equal to the time required to discharge the stray capacitance at SYNC through R SYNC plus the C T discharge time t D . Adjust R T /C T such that the minimum discharge time t Dis 200ns.MAX5094A/B/C/D/MAX5095A/B/CPWM ControllersM A X 5094A /B /C /D /M A X 5095A /B /CAdvance Clock Output (ADV_CLK) (MAX5095C)ADV_CLK is an advanced pulse output provided to facilitate the easy implementation of secondary-side synchronous rectification using the MAX5095C. The ADV_CLK pulse width is 85ns (typically) with its rising edge leading the rising edge of OUT by 110ns. Use this leading pulse to turn off the secondary-side syn-chronous-rectifier MOSFET (QS) before the voltage appears on the secondary (see Figure 8). Turning off the secondary-side synchronous MOSFET earlier avoids the shorting of the secondary in the forward converter. The ADV_CLK pulse can be propagated to the secondary side using a pulse transformer or high-speed optocoupler. The 85ns pulse, with 3V drive volt-age (10mA source), significantly reduces the volt-second requirement of the pulse transformer and the advanced pulse alleviates the need for a high-speed optocoupler.Thermal ShutdownWhen the MAX5094/MAX5095’s die temperature goes above +150°C, the thermal shutdown circuitry will shut down the 5V reference and pull OUT low.PWM ControllersTypical Application CircuitsFigure 5. MAX5094_ Typical Application Circuit (Isolated Flyback with Primary-Side Regulation)MAX5094A/B/C/D/MAX5095A/B/C PWM Controllers Typical Application Circuits (continued)Figure 6. MAX5094_ Typical Application Circuit (Nonisolated Flyback)Figure 7. MAX5095A/MAX5095B Typical Application Circuit (Isolated Flyback)M A X 5094A /B /C /D /M A X 5095A /B /CPWM Controllers Typical Application Circuits (continued)Figure 8. MAX5095C Typical Application Circuit (Isolated Forward with Secondary-Side Synchronous Rectification)MAX5094A/B/C/D/MAX5095A/B/C PWM ControllersFigure 9. Synchronization of MAX5095A/MAX5095BM A X 5094A /B /C /D /M A X 5095A /B /CPWM Controllers Chip InformationTRANSISTOR COUNT:1987PROCESS:BiCMOSSelector GuideOrdering Information (continued)+Denotes lead-free package.*Future product—contact factory for availability.Package InformationMAX5094A/B/C/D/MAX5095A/B/C PWM Controllers (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline informationgo to /packages.)M A X 5094A /B /C /D /M A X 5095A /B /CPWM Controllers 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.22____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600©2006 Maxim Integrated Productsis a registered trademark of Maxim Integrated Products, Inc.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 .)。
●Saves Board Space •Integrated Charge Pump CircuitryEliminates the Need for a Bipolar ±12V SupplyEnables Single Supply Operation From Either +5Vor 9V to +12V•Integrated 0.1μF Capacitors (MAX203, MAX205)•24 pin SSOP Package Saves Up to 40% VersusSO Package●Saves Power for Longer Battery Operation•5μW Shutdown Mode (MAX200, MAX205,MAX206, MAX211)•75μW Ring Indicator Monitoring with Two ActiveReceivers (MAX213)Applications ●Battery-Powered Equipment ●Handheld Equipment ●Portable Diagnostics Equipment Selector Guide continued at end of data sheet.19-0065; Rev 8; 1/15PART POWER-SUPPLYVOLTAGE (V)NUMBER OF RS-232 DRIVERS NUMBER OF RS-232 RECEIVERS NUMBER OF RECEIVERS ACTIVE IN SHUTDOWN NUMBER OF EXTERNAL CAPACITORS (0.1μF)LOW-POWER SHUTDOWN/TTL THREE-STATE MAX200+55004Yes/No MAX201+5 and +9.0 to +13.22202No/No MAX202+52204No/No MAX203+5220None No/No 找MEMORY 、二三极管上美光存储MAX200-MAX209, MAX211, and MAX213 are a familyof RS-232 and V.28 transceivers with integrated chargepump circuitry for single +5V supply operation.The drivers maintain the ±5V EIA/TIA-232E outputsignal levels at data rates in excess of 120kbps whenloaded in accordance with the EIA/TIA-232Especification.The MAX211 and MAX213 are available in a 28-pin,wide small-outline (SO) package and a 28-pin shrinksmall-outline (SSOP) package, which occupies only 40%of the area of the SO. The MAX207 is available in a 24-pin SO package and a 24-pin SSOP . The MAX203 andMAX205 use no external components and arerecommended for applications with limited circuit boardspace.Bene its and FeaturesSelector GuideTypical Operating Circuit安装风格：S M O/S M T 。
