Regulating Pulse Width Modulator datasheet - …

1 BLOCK DIAGRAMUC1526 AUC2526 AUC3526 ARegulating Pulse Width ModulatorFEATURES Reduced Supply Current Oscillator Frequency to 600kHz Precision Band-Gap Reference 7 to 35V Operation Dual 200mA Source/Sink Outputs Minimum Output Cross-Conduction Double- Pulse Suppression Logic Under-Voltage Lockout Programmable Soft-Start Thermal Shutdown TTL/CMOS Compatible Logic Ports 5 Volt Operation (VIN = VC = VREF = )DESCRIPTIONThe UC1526A Series are improved-performance Pulse - Width modu-lator circuits intended for direct replacement of equivalent non- A versions in all applications.

2 Higher frequency operation has beenenhanced by several significant improvements including: a more ac-curate oscillator with less minimum dead time, reduced circuit de-lays (particularly in current limiting), and an improved output stagewith negligible cross-conduction current. Additional improvementsinclude the incorporation of a precision, band-gap reference gener-ator, reduced overall supply current, and the addition of thermalshutdown with these improvements, the UC1526A Series retains theprotective features of under-voltage lockout, soft-start, digital cur-rent limiting, double Pulse suppression logic, and adjustabledeadtime.

3 For ease of interfacing, all digital control ports are TTLcompatible with active low volt (5V) operation is possible for logic level applications byconnecting VIN, VC and VREF to a precision 5V input supply. Consultfactory for additional OPERATING CONDITIONS (Note 3)Input Voltage .. +7V to +35 VCollector Supply Voltage .. + to +35 VSink/Source Load Current (each output) .. 0 to 100mAReference Load Current .. 0 to 20mAOscillator Frequency Range .. 1Hz to 600kHzOscillator Timing Resistor.. 2k to 150k Oscillator Timing Capacitor.

4 400pF to 20 FAvailable Deadtime Range at 40kHz .. 1% to 50%Operating Ambient Temperature Range UC1526A.. -55 C to +125 C UC2526A.. -25 C to +85 C UC3526A.. 0 C to +70 CABSOLUTE MAXIMUM RATINGS (Note 1, 2)Input Voltage (+VIN).. +40 VCollector Supply Voltage (+VC) .. +40 VLogic Inputs .. to + Inputs .. to +VINS ource/Sink Load Current (each output) .. 200mAReference Load Current .. 50mALogic Sink Current .. 15mAPower Dissipation at TA = +25 C (Note 2) .. 1000mWPower Dissipation at TC = +25 C (Note 2) .. 3000mWOperating Junction Temperature.

5 +150 CStorage Temperature Range .. -65 C to +150 CLead Temperature (soldering, 10 seconds) .. +300 CCONNECTION DIAGRAMSPACKAGE PIN FUNCTIONFUNCTIONPINN/C1+ CURRENT SENSE7+ CURRENT SENSE8 SHUTDOWN9 RTIMING10CT11RD12 SYNC13 OUTPUT A14VC15N/C16 GROUND17 OUTPUT B18+VIN19 VREF20 PLCC-20, LCC-20 (TOP VIEW) Q and L PackagesDIL-18, SOIC-18 (TOP VIEW)J or N Package, DW PackageNote 1: Values beyond which damage may 2: Consult packaging Section of Databook for thermal limitations and considerations of 3: Range over which the device is functional and parameter limits are CONDITIONSUC1526A / UC2526 AUC3526 AUNITSMINTYPMAXMINTYPMAXR eference Section (Note 4)Output VoltageTJ = +25 Regulation+VIN = 7 to 35V210215mVLoad RegulationIL = 0 to 20mA520520mVTemperature StabilityOver Operating TJ (Note 5)15501550mVTotal Output VoltageRangeOver Recommended Circuit CurrentVREF = 0V25501002550100mAUnder-Voltage LockoutRESET Output VoltageVREF = = Section (Note 6)

6 Initial AccuracyTJ = +25 C 3 8 3 8%Voltage Stability+VIN = 7 to StabilityOver Operating TJ (Note 5)2613%Minimum FrequencyRT = 150k , CT = 20 F (Note 5)11 HzMaximum FrequencyRT = 2k , CT = 470pF550650kHzSawtooth Peak Voltage+VIN = Valley Voltage+VIN = Pulse WidthTJ = 25 C, RL = to sError Amplifier Section (Note 7)Input Offset VoltageRS 2k 25210mVInput Bias Current-350-1000-350-2000nAInput Offset Current3510035200nADC Open Loop GainRL 10M 64726072dBHIGH Output VoltageVPIN 1 - VPIN 2 150mV, ISOURCE = 100 Output VoltageVPIN 2 - VPIN 1 150mV, ISINK = 100 Mode RejectionRS 2k 70947094dBSupply Voltage Rejection+VIN = 12 to 18V66806680dBPWM Comparator (Note 6)Minimum Duty CycleVCOMPENSATION = + Duty CycleVCOMPENSATION = + Ports (SYNC, SHUTDOWN, and RESET)

7 HIGH Output VoltageISOURCE = 40 Output VoltageISINK = Input CurrentVIH = + ALOW Input CurrentVIL = + AShutdown DelayFrom Pin 8, TJ = 25 C160160nsCurrent Limit Comparator (Note 8)Sense VoltageRS 50 9010011080100120mVInput Bias Current-3-10-3-10 AShutdown DelayFrom pin 7, 100mV Overdrive, TJ = 25 C260260ns+VIN = 15V, and over operating ambient temperature, unless otherwise specified TA = CHARACTERISTICS:Note 4: IL = 5: Guaranteed by design, not 100% tested in 6: FOSC = 40kHz, (RT = 1%, CT = F 1%,RD = 0 ).Note 7: VCM = 0 to + 8: VCM = 0 to + 9: VC = + 10:VIN = +35V, RT =.

8 UC1526 AUC2526 AUC3526A3 ELECTRICAL CHARACTERISTICS:PARAMETERTEST CONDITIONSUC1526 AUC2526 AUC3526 AUNITSMINTYPMAXMINTYPMAXSoft-Start SectionError Clamp VoltageRESET = + Charging CurrentRESET = + AOutput Drivers (Each Output) (Note 9)HIGH Output VoltageISOURCE = = 100mA12131213 VLOW Output VoltageISINK = = LeakageVC = 40V5015050150 ARise TimeCL = 1000pF (Note 5) sFall TimeCL = 1000pF (Note 5) sCross-Conduction Charge Per cycle, TJ = 25 C88nCPower Consumption (Note 10)Standby CurrentSHUTDOWN = + 4: IL = 5: Guaranteed by design, not 100% tested in 6: FOSC = 40kHz, (RT = 1%, CT = F 1%,RD = 0 ).

9 Note 7: VCM = 0 to + 8: VCM = 0 to + 9: VC = + 10:VIN = +35V, RT = .Open Loop Test Circuit UC1526A+VIN = 15V, and over operating ambient temperature, unless otherwise specified TA = INFORMATIONV oltage ReferenceThe reference regulator of the UC1526A is based on aprecision band-gap reference, internally trimmed to 1%accuracy. The circuitry is fully active at supply voltagesabove +7V, and provides up to 20mA of load current toexternal circuitry at + In systems where additionalcurrent is required, an external PNP transistor can beused to boost the available current.

10 A rugged low fre-quency audio-type transistor should be used, and leadlengths between the PWM and transistor should be asshort as possible to minimize the risk of so, some types of transistors may require collec-tor-base capacitance for stability. Up to 1 amp of loadcurrent can be obtained with excellent regulation if thedevice selected maintains high current CircuitThe soft-start circuit protects the power transistors andrectifier diodes from high current surges during powersupply turn-on.