MAX5071AAUA+ ,High-Performance, Single-Ended, Current-Mode PWM Controllersfeaturesand UC2844 (MAX5070B)required for wide input voltage range isolated/nonisolated♦ 2A Drive S ..
MAX5071BAUA ,5 V, high-performance, single-ended, current-mode PWM controllerMAX5070/MAX507119-3283; Rev 1; 6/04High-Performance, Single-Ended, Current-ModePWM Controllers
MAX5072ETJ+ ,2.2MHz, Dual-Output Buck or Boost Converter with POR and Power-Fail OutputApplicationsSOURCE1 26 15 BYPASSxDSL Modems27 14SOURCE1 VLxDSL RoutersPGND 28 13 VLPoint-of-Load DC ..
MAX5073ETI ,2.2MHz, Dual-Output Buck or Boost Converter with Internal Power MOSFETsFeatures● 4.5V to 5.5V or 5.5V to 23V Input Supply The MAX5073 is a dual-output DC-DC converter wi ..
MAX5073ETI+T ,2.2MHz, Dual-Output Buck or Boost Converter with Internal Power MOSFETsApplications SOURCE1 23 13 VL● Point-of-Load DC-DC ConvertersSOURCE1 24 12 VL● Telecom Line CardSGN ..
MAX5078AATT ,4 to 15 V, 4 A, 20 ns, MOSFET driverFeaturesThe MAX5078A/MAX5078B high-speed MOSFET drivers♦ 4V to 15V Single Power Supplysource and si ..
MAX934CSE ,Ultra Low-Power, Low-Cost Comparators with 2eferenceFeaturesThe MAX931-MAX934 single, dual, and quad micropower, ' Ultra-Low 4µA Max Quiescent Currentl ..
MAX934CSE ,Ultra Low-Power, Low-Cost Comparators with 2eferenceApplications5 HYSTBattery-Powered SystemsThreshold Detectors6 REFMAX931Window ComparatorsV- GND21Os ..
MAX934CSE ,Ultra Low-Power, Low-Cost Comparators with 2eferenceELECTRICAL CHARACTERISTICS—5V Operation (continued)(V+ = 5V, V- = GND = 0V, T = T to T , unless oth ..
MAX934CSE+ ,Ultra-Low-Power, Low-Cost Comparators with 2% ReferenceELECTRICAL CHARACTERISTICS—5V Operation(V+ = 5V, V- = GND = 0V, T = T to T , unless otherwise noted ..
MAX934CSE+T ,Ultra-Low-Power, Low-Cost Comparators with 2% ReferenceGeneral Description ________
MAX934CSET ,Ultra-Low-Power, Low-Cost Comparators with 2% ReferenceELECTRICAL CHARACTERISTICS—5V Operation(V+ = 5V, V- = GND = 0V, T = T to T , unless otherwise noted ..
MAX5071AAUA+
High-Performance, Single-Ended, Current-Mode PWM Controllers
General DescriptionThe MAX5070/MAX5071 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 voltage and telecom power
supplies.
The MAX5070/MAX5071 contain a fast comparator with
only 60ns typical delay from current sense to the output
for overcurrent protection. The MAX5070A/MAX5070B
have an integrated error amplifier with the output at
COMP. Soft-start is achieved by controlling the COMP
voltage rise using external components.
The frequency is adjustable from 20kHz to 1MHz with
an external resistor and capacitor. The timing capacitor
discharge current is trimmed allowing for programma-
ble dead time and maximum duty cycle for a given fre-
quency. The available saw-toothed waveform at RTCT
can be used for slope compensation when needed.
The MAX5071A/MAX5071B 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 pins of all devices together. When synchro-
nizing with other devices, the MAX5071A/MAX5071B
with the highest frequency synchronizes the other
devices. Alternatively, the MAX5071A/MAX5071B can
be synchronized to an external clock with an open-
drain output stage running at a higher frequency.
The MAX5071C 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 MAX5070/MAX5071 are available in 8-pin µMAX®
and SO packages and operate over the automotive tem-
perature range of -40°C to +125°C.
ApplicationsUniversal Input AC/DC Power Supplies
Isolated Telecom Power Supplies
Isolated Power-Supply Modules
Networking Systems
Computer Systems/Servers
Industrial Power Conversion
Isolated Keep-Alive Circuits
FeaturesPin-for-Pin Replacement for UC2842 (MAX5070A)
and UC2844 (MAX5070B)2A Drive Source and 1A Sink CapabilityUp to 1MHz Switching Frequency OperationBidirectional Synchronization
(MAX5071A/MAX5071B)Advanced Output Drive for Secondary-Side
Synchronous Rectification (MAX5071C)Fast 60ns Cycle-by-Cycle Current LimitTrimmed Oscillator Capacitor Discharge Current
Sets Maximum Duty Cycle AccuratelyAccurate 5% Start and Stop Voltage with 6V
HysteresisLow 32μA Startup Current5V Regulator Output (VREF) with 20mA CapabilityOvertemperature Shutdown
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM ControllersOUT
GNDRT/CT
VREF
VCCFB
COMP
µMAX/SO
TOP VIEW
MAX5070A
MAX5070B
Pin Configurations
Ordering Information19-3283; Rev 3; 10/06
Ordering Information continued at end of data sheet.
Selector Guide appears at end of data sheet.Specify lead-free by adding the + symbol at the end of the part
number when ordering.
PARTTEMP RANGEPIN-PACKAGE
MAX5070AASA-40°C to +125°C8 SO
MAX5070AAUA-40°C to +125°C8 µMAX
MAX5070BASA-40°C to +125°C8 SO
MAX5070BAUA-40°C to +125°C8 µMAX
Pin Configurations continued at end of data sheet.µMAX is a registered trademark of Maxim Integrated Products, Inc.
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VCC= +15V, RT= 10kΩ, CT= 3.3nF, VVREF= OPEN, CVREF= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA
= -40°C to +85°C,unless otherwise noted.) (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.
VCC(Low-Impedance Source) to GND..................-0.3V to +30V
VCC(ICC< 30mA).....................................................Self Limiting
OUT to GND...............................................-0.3V to (VCC+ 0.3V)
OUT Current.............................................................±1A for 10µs
FB, SYNC, COMP, CS, RT/CT, VREF to GND...........-0.3V to +6V
COMP Sink Current (MAX5070)..........................................10mA
Continuous Power Dissipation (TA = +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 (Automotive)....-40°C to +125°C
Maximum Junction Temperature.....................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
REFERENCEOutput VoltageVVREFTA = +25°C, IVREF = 1mA4.9505.0005.050V
Line Regulation∆VLINE12V < VCC < 25V, IVREF = 1mA0.44mV
Load Regulation∆VLOAD1mA < IVREF < 20mA625mV
Total Output VariationVREFT1mA < IVREF < 20mA, 12V < VCC < 25V4.95.1V
Reference Output-Noise VoltageVNOISE10Hz < f < 10kHz, TA = +25°C50µV
Reference Output Short CircuitIS_SCVVREF = 0V-30-100-180mA
OSCILLATORInitial AccuracyTA = +25°C515457kHz
Voltage Stability12V < VCC < 25V0.20.5%
Temp Stability-40°C < TA < +85°C0.5%
RT/CT Voltage Ramp (P-P)VRAMP1.7V
RT/CT Voltage Ramp ValleyVRAMP_VALLEY1.1V
Discharge CurrentIDISVRT/CT = 2V, TA = +25°C7.98.38.7mA
Frequency RangefOSC201000kHz
ERROR AMPLIFIER (MAX5070A/MAX5070B)FB Input VoltageVFBFB shorted to COMP2.4652.52.535V
FB Input Bias CurrentIB(FB)-0.01-0.1µA
Open-Loop Voltage GainAVOL2V ≤ VCOMP ≤ 4V100dB
Unity-Gain BandwidthfGBW1MHz
Power-Supply Rejection RatioPSRR12V ≤ VCC ≤ 25V (Note 2)6080dB
COMP Sink CurrentISINKVFB = 2.7V, VCOMP = 1.1V26mA
COMP Source CurrentISOURCEVFB = 2.3V, VCOMP = 5V-0.5-1.2-1.8mA
COMP Output High VoltageVCOMPHVFB = 2.3V, RCOMP = 15kΩ to GND55.8V
COMP Output Low VoltageVCOMPLVFB = 2.7V, RCOMP = 15kΩ to VREF0.10.5V
CURRENT-SENSE AMPLIFIERGainACS(Notes 3, 4)2.8533.26V/V
MAX5070A/B (Note 3)0.9511.05Maximum Current-Sense SignalVCS_MAXVCOMP = 5V, MAX5071_0.9511.05V
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
ELECTRICAL CHARACTERISTICS (continued)(VCC= +15V, RT= 10kΩ, CT= 3.3nF, VVREF= OPEN, CVREF= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA
= -40°C to +85°C,unless otherwise noted.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSPower-Supply Rejection RatioPSRR12V ≤ VCC ≤ 25V70dB
Input Bias CurrentICSVCOMP = 0V-1-2.5µA
Delay From CS to OUTtCS_DELAY50mV overdrive60ns
MOSFET DRIVEROUT Low-Side On-ResistanceVRDS_ONLISINK = 200mA4.510Ω
OUT High-Side On-ResistanceVRDS_ONHISOURCE = 100mA3.57Ω
ISOURCE (Peak)ISOURCECOUT = 10nF2A
ISINK (Peak)ISINKCOUT = 10nF1A
Rise TimetrCOUT = 1nF15ns
Fall TimetfCOUT = 1nF22ns
UNDERVOLTAGE LOCKOUT/STARTUPStartup Voltage ThresholdVCC_START15.21616.8V
Minimum Operating Voltage After
Turn-OnVCC_MIN9.21010.8V
Undervoltage-Lockout HysteresisUVLOHYST6V
PWMMAX5070A/MAX5071A94.59697.5Maximum Duty CycleDMAXMAX5070B/MAX5071B/MAX5071C4849.850%
Minimum Duty CycleDMIN0%
SUPPLY CURRENTStartup Supply CurrentISTART3265µA
Operating Supply CurrentICCVFB = VCS = 0V35mA
Zener Bias Voltage at VCCVZICC = 25mA2426.5V
THERMAL SHUTDOWNThermal ShutdownTSHDN+150°C
Thermal-Shutdown HysteresisTHYST4°C
SYNCHRONIZATION (MAX5071A/MAX5071B only) (Note 5)SYNC Frequency RangefSYNC201000kHz
SYNC Clock Input High
ThresholdVSYNCINH3.5V
SYNC Clock Input Low ThresholdVSYNCINL0.8V
SYNC Clock Input Minimum
Pulse WidthtPW_SYNCIN200ns
SYNC Clock Output High LevelVSYNCOH1mA external pulldown4.04.7V
SYNC Clock Output Low LevelVSYNCOLRSYNC = 5kΩ00.1V
SYNC Leakage CurrentISYNCVSYNC = 0V0.010.1µA
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
ELECTRICAL CHARACTERISTICS (continued)(VCC= +15V, RT= 10kΩ, CT= 3.3nF, VVREF= OPEN, CVREF= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA
= -40°C to +85°C,unless otherwise noted.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
ADV_CLK (MAX5071C only)ADV_CLK High VoltageVADV_CLKHIADV_CLK = 10mA source2.43V
ADV_CLK Low VoltageVADV_CLKLIADV_CLK = 10mA sink0.4V
ADV_CLK Output Pulse WidthtPULSE85ns
ADV_CLK Rising Edge to OUT
Rising EdgetADV_CLK110ns
ADV_CLK Source and Sink
CurrentIADV_CLK10mA
ELECTRICAL CHARACTERISTICS(VCC= +15V, RT= 10kΩ, CT= 3.3nF, VVREF= OPEN, CVREF= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA
= -40°C to +125°C,unless otherwise noted.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
REFERENCEOutput VoltageVVREFTA = +25°C, IVREF = 1mA4.9505.0005.050V
Line Regulation∆VLINE12V < VCC < 25V, IVREF = 1mA0.44mV
Load Regulation∆VLOAD1mA < IVREF < 20mA625mV
Total Output VariationVREFT1mA < IVREF < 20mA, 12V < VCC < 25V4.95.1V
Reference Output Noise VoltageVNOISE10Hz < f < 10kHz, TA = +25°C50µV
Reference Output Short CircuitIS_SCVVREF = 0V-30-100-180mA
OSCILLATORInitial AccuracyTA = +25°C515457kHz
Voltage Stability12V < VCC < 25V0.20.5%
Temp Stability-40°C < TA < +125°C1%
RT/CT Voltage Ramp (P-P)VRAMP1.7V
RT/CT Voltage Ramp ValleyVRAMP_VALLEY1.1V
Discharge CurrentIDISVRT/CT = 2V, TA = +25°C7.98.38.7mA
Frequency RangefOSC201000kHz
ERROR AMPLIFIER (MAX5070A/MAX5070B)FB Input VoltageVFBFB shorted to COMP2.4652.52.535V
FB Input Bias CurrentIB(FB)-0.01-0.1µA
Open-Loop Voltage GainAVOL2V ≤ VCOMP ≤ 4V100dB
Unity-Gain BandwidthfGBW1MHz
Power-Supply Rejection RatioPSRR12V ≤ VCC ≤ 25V (Note 2)6080dB
COMP Sink CurrentISINKVFB = 2.7V, VCOMP = 1.1V26mA
COMP Source CurrentISOURCEVFB = 2.3V, VCOMP = 5V-0.5-1.2-1.8mA
COMP Output High VoltageVCOMPHVFB = 2.3V, RCOMP =15kΩ to GND55.8V
COMP Output Low VoltageVCOMPLVFB = 2.7V, RCOMP = 15kΩ to VREF0.10.5V
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
ELECTRICAL CHARACTERISTICS (continued)(VCC= +15V, RT= 10kΩ, CT= 3.3nF, VVREF= OPEN, CVREF= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA
= -40°C to +125°C,unless otherwise noted.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
CURRENT-SENSE AMPLIFIERGainACS(Notes 3, 4)2.8533.26V/V
MAX5070A/B (Note 3)0.9511.05Maximum Current-Sense SignalVCS_MAXVCOMP = 5V, MAX5071_0.9511.05V
Power-Supply Rejection RatioPSRR12V ≤ VCC ≤ 25V70dB
Input Bias CurrentICS-1-2.5µA
Delay From CS to OUTtCS_DELAY50mV overdrive60ns
MOSFET DRIVEROUT Low-Side On-ResistanceVRDS_ONLISINK = 200mA4.512Ω
OUT High-Side On-ResistanceVRDS_ONHISOURCE = 100mA3.59Ω
ISOURCE (Peak)ISOURCECOUT = 10nF2A
ISINK (Peak)ISINKCOUT = 10nF1A
Rise TimetrCOUT = 1nF15ns
Fall TimetfCOUT = 1nF22ns
UNDERVOLTAGE LOCKOUT/STARTUPStartup Voltage ThresholdVCC_START15.21616.8V
Minimum Operating Voltage After
Turn-OnVCC_MIN9.21010.8V
Undervoltage-Lockout HysteresisUVLOHYST6V
PWMMAX5070A/MAX5071A94.59697.5Maximum Duty CycleDMAXMAX5070B/MAX5071B/MAX5071C4849.850%
Minimum Duty CycleDMIN0%
SUPPLY CURRENTStartup Supply CurrentISTART3265µA
Operating Supply CurrentICCVFB = VCS = 0V35mA
Zener Bias Voltage at VCCVZICC = 25mA2426.5V
THERMAL SHUTDOWNThermal ShutdownTSHDN+150°C
Thermal-Shutdown HysteresisTHYST4°C
SYNCHRONIZATION (MAX5071A/MAX5071B only, Note 5)SYNC Frequency RangefSYNC201000kHz
SYNC Clock Input High
ThresholdVSYNCINH3.5V
SYNC Clock Input Low ThresholdVSYNCINL0.8V
SYNC Clock Input Minimum
Pulse WidthtPW_SYNCIN200ns
SYNC Clock Output High LevelVSYNCOH1mA external pulldown4.04.7V
SYNC Clock Output Low LevelVSYNCOLRSYNC = 5kΩ00.1V
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
ELECTRICAL CHARACTERISTICS (continued)(VCC= +15V, RT= 10kΩ, CT= 3.3nF, VVREF= OPEN, CVREF= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA
= -40°C to +125°C,unless otherwise noted.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSYNC Leakage CurrentISYNCVSYNC = 0V0.010.1µA
ADV_CLK (MAX5071C only)ADV_CLK High VoltageVADV_CLKHIADV_CLK = 10mA source2.43V
ADV_CLK Low VoltageVADV_CLKLIADV_CLK = 10mA sink0.4V
ADV_CLK Output Pulse WidthtPULSE85ns
ADV_CLK Rising Edge to OUT
Rising EdgetADV_CLK110ns
ADV_CLK Source and Sink
CurrentIADV_CLK10mA
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 VFB= 0V (MAX5070A/MAX5070B only).
Note 4:Gain is defined as A = ∆VCOMP/∆VCS, 0 ≤VCS≤0.8V.
Note 5:Output Frequency equals oscillator frequency for MAX5070A/MAX5071A. Output frequency is one-half oscillator frequency
for MAX5070B/MAX5071B/MAX5071C.
BOOTSTRAP UVLO vs. TEMPERATUREMAX5070 toc01
TEMPERATURE (°C)
(V)
HYSTERESIS
VCC FALLING
VCC RISING
STARTUP CURRENT vs. TEMPERATUREMAX5070 toc02
TEMPERATURE (°C)
STARTUP CURRENT (
OPERATING SUPPLY CURRENT (ICC)
vs. TEMPERATURE AFTER STARTUP
(fOSC = fSW = 250kHz)
MAX5070 toc03
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
CT = 100pF
Typical Operating Characteristics(VCC= 15V, TA = +25°C, unless otherwise noted.)
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
REFERENCE VOLTAGE (VREF)
vs. TEMPERATUREMAX5070 toc04
TEMPERATURE (°C)
VREF
(V)
IREF = 20mA
IREF = 1mA
REFERENCE VOLTAGE (VREF)
vs. REFERENCE LOAD CURRENTMAX5070 toc05
IREF (mA)
VREF
(V)3015
REFERENCE VOLTAGE (VREF)
vs. VCC VOLTAGE
MAX5070 toc06
VCC (V)
VREF
(V)222018161412
IREF = 1mA
OSCILLATOR FREQUENCY (fOSC)
vs. TEMPERATUREMAX5070 toc07
TEMPERATURE (°C)
OSCILLATOR FREQUENCY (kHz)
RT = 3.01kΩ
CT = 1nF
OSCILLATOR RT/CT DISCHARGE CURRENT
vs. TEMPERATUREMAX5070 toc08
TEMPERATURE (°C)
DISCHARGE CURRENT (mA)
VRT/CT = 2V
MAXIMUM DUTY CYCLE
vs. TEMPERATUREMAX5070 toc09
TEMPERATURE (°C)
DUTY CYCLE (%)
RT = 3.01kΩ
CT = 1nFMAX5070A/MAX5071A
MAX5070B/MAX5071B/MAX5071C
MAX5070A/MAX5071A
MAXIMUM DUTY CYCLE vs. FREQUENCYMAX5070 toc10
OSCILLATOR FREQUENCY (kHz)
DUTY CYCLE (%)
CT = 100pF
CT = 1nFCT = 560pF
CT = 220pF
CURRENT-SENSE (CS) TRIP THRESHOLD
vs. TEMPERATUREMAX5070 toc11
TEMPERATURE (°C)
CS THRESHOLD (V)
Typical Operating Characteristics (continued)
(VCC= 15V, TA = +25°C, unless otherwise noted.)
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
Typical Operating Characteristics (continued)(VCC= 15V, TA = +25°C, unless otherwise noted.)
TIMING RESISTANCE (RT)
vs. OSCILLATOR FREQUENCYMAX5070 toc12
FREQUENCY (Hz)
T RESISTANCE (k100k
10k10M
CT = 10nF
CT = 4.7nF
CT = 3.3nF
CT = 2.2nF
CT = 1nF
CT = 560pF
CT = 220pF
CT = 100pF
OUT IMPEDANCE vs. TEMPERATURE
(RDS_ON PMOS DRIVER)MAX5070 toc13
TEMPERATURE (°C)
DS_ON
ISOURCE = 100mA
OUT IMPEDANCE vs. TEMPERATURE
(RDS_ON NMOS DRIVER)MAX5070 toc14
TEMPERATURE (°C)
DS_ON
ISINK = 200mA
PROPAGATION DELAY FROM CURRENT-LIMIT
COMPARATOR TO OUT vs. TEMPERATUREMAX5070 toc15
TEMPERATURE (°C)
PROPAGATION DELAY (ns)
ERROR-AMPLIFIER OPEN-LOOP GAIN
AND PHASE vs. FREQUENCY
MAX5070 toc16
FREQUENCY (Hz)
GAIN (dB)100k1k10k101001
0.01100M10M
PHASE
GAIN
PHASE (DEGREES)
COMP VOLTAGE LEVEL TO TURN OFF DEVICE
vs. TEMPERATUREMAX5070 toc17
TEMPERATURE (°C)
COMP
(V)
10V < VCC < 18V
ADV_CLK RISING EDGE TO OUT RISING EDGE
PROPAGATION DELAY vs. TEMPERATUREMAX5070 toc18
TEMPERATURE (°C)
PROPAGATION DELAY (ns)
MAX5071C
ADV_CLK AND OUT WAVEFORMSMAX5070 toc19
VCC = 15V
MAX5071C
OUT
10V/div
10kΩ LOAD
ADV_CLK
5V/div
20ns/div
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
OUT SOURCE AND SINK CURRENTSMAX5070 toc20
VCC = 15V
IOUT
2A/div
VOUT
10V/div
20Ons/div
COUT = 10nF2203204205201206207208209201020
SUPPLY CURRENT (ICC)
vs. OSCILLATOR FREQUENCY (CT = 100pF)MAX5070 toc21
FREQUENCY (kHz)
SUPPLY CURRENT (mA)
TA = +125°C
TA = +85°C
TA = +25°C
TA = -40°C
MAX5070A/MAX5071A
MAXIMUM DUTY CYCLE vs. RTMAX5070 toc22
RT (Ω)
DUTY CYCLE (%)
10k1k
100100k
CT = 1nF
CT = 560pF
CT = 220pF
CT = 100pF
Typical Operating Characteristics (continued)(VCC= 15V, TA = +25°C, unless otherwise noted.)
Pin Descriptions
PINNAMEFUNCTIONCOMPError-Amplifier Output. COMP can be used for soft-start.FBError-Amplifier Inverting Input
3CSInput to the PWM Comparator and Overcurrent Protection Comparator. The current-sense signal is
compared to a signal proportional to the error-amplifier output voltage.
4RT/CTTiming Resistor and Capacitor Connection. A resistor RT from RT/CT to VREF and capacitor CT from
RT/CT to GND set the oscillator frequency.GNDPower-Supply Ground. Place the VCC and VREF bypass capacitors close to the IC to minimize
ground loops.OUTMOSFET Driver Output. OUT connects to the gate of the external n-channel MOSFET.
7VCCPower-Supply Input for MAX5070. Bypass VCC to GND with a 0.1µF ceramic capacitor or a parallel
combination of a 0.1µF and a higher value ceramic capacitor.VREF5V Reference Output. Bypass VREF to GND with a 0.1µF ceramic capacitor or a parallel combination
of a 0.1µF and a higher value ceramic capacitor.
MAX5070A/MAX5070B
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
Pin Descriptions (continued)
PIN
MAX5071A/
MAX5071BMAX5071CNAMEFUNCTION1COMP
COMP is level-shifted and connected to the inverting input of the PWM comparator. Pull
up COMP to VREF through a resistor and connect an optocoupler from COMP to GND for
proper operation.—SYNCBidirectional Synchronization Input. When synchronizing with other
MAX5071A/MAX5071Bs, the higher frequency part synchronizes all other devices.ADV_CLK
ADV_CLK is an 85ns clock output pulse preceding the rising edge of OUT (see Figure 4).
Use the pulse to drive the secondary-side synchronous rectifiers through a pulse
transformer or an optocoupler (see Figure 8).CSInput to the PWM Comparator and Overcurrent Protection Comparator. The current-
sense signal is compared to the voltage at COMP.RT/CTTiming Resistor and Capacitor Connection. A resistor RT from RT/CT to VREF and
capacitor CT from RT/CT to GND set the oscillator frequency.5GNDPower-Supply Ground. Place the VCC and VREF bypass capacitors close to the IC to
minimize ground loops.6OUTMOSFET Driver Output. OUT connects to the gate of the external n-channel MOSFET.VCCPower-Supply Input for MAX5071. Bypass VCC to GND with a 0.1µF ceramic capacitor or
a parallel combination of a 0.1µF and a higher value ceramic capacitor.VREF5V Reference Output. Bypass VREF to GND with a 0.1µF ceramic capacitor or a parallel
combination of a 0.1µF and a higher value ceramic capacitor.
MAX5071A/MAX5071B/MAX5071C
Detailed DescriptionThe MAX5070/MAX5071 current-mode PWM controllers
are designed for use as the control and regulation core of
flyback or forward topology switching power supplies.
These devices incorporate an integrated low-side driver,
adjustable oscillator, error amplifier (MAX5070A/
MAX5070B only), current-sense amplifier, 5V reference,
and external synchronization capability (MAX5071A/
MAX5071B only). An internal +26.5V current-limited VCC
clamp prevents overvoltage during startup.
Five different versions of the MAX5070/MAX5071 are
available. The MAX5070A/MAX5070B are the standard
versions with a feedback input (FB) and internal error
amplifier. The MAX5071A/MAX5071B include bidirection-
al synchronization (SYNC). This enables multiple
MAX5071A/MAX5071Bs to be connected and synchro-
nized to the device with the highest frequency. The
MAX5071C includes an ADV_CLK output, which pre-
cedes the MAX5071C’s drive output (OUT) by 110ns.
Figures 1, 2, and 3 show the internal functional diagrams
of the MAX5070A/MAX5070B, MAX5071A/MAX5071B,
and MAX5071C, respectively. The MAX5070A/
MAX5071A are capable of 100% maximum duty cycle.
The MAX5070B/MAX5071B/MAX5071C are designed to
limit the maximum duty cycle to 50%.
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM ControllersUVLO
REFERENCE
2.5V
PREREGULATOR
VOLTAGE-
DIVIDER
THERMAL
SHUTDOWN
EN-REF
SNS
VDD
5V REGULATOR
VOLTAGE-
DIVIDER
26.5V
VCC
VREF
2.5VREG_OK
DELAY
OSCQRT/CTOUTILIM
CPWM
EN-DRV-BAR
VEA
GND
COMP
CLK
MAX5070A/MAX5070B
2.5V
16V/10V
100% MAX DUTY CYCLE (MAX5070A)
50% MAX DUTY CYCLE (MAX5070B)
Figure 1. MAX5070A/MAX5070B Functional Diagram
