FEATURESDESCRIPTIONBLOCK DIAGRAMDESCRIPTION (continued)ABSOLUTE MAXIMUM RATINGSRECOMMENDED OPERATING CONDITIONSTHERMAL CHARACTERISTICSCONNECTION DIAGRAMSELECTRICAL CHARACTERISTICSPRINCIPLES OF OPERATION AND TYPICAL CHARACTERISTICSShutdown Options (See Block Diagram)1FEATURESDESCRIPTIONBLOCK DIAGRAM15123657912810ReferenceRegulator16 4OSC50 mA131411131114COMPSSR+VINGROUNDSYNCRTCTDISCHARGECOMPENSATIONINV INPUTNI INPUTSOFTSTARTSHUTDOWN OUTPUT BOUTPUT AVCOUTPUT BOUTPUT AVCNORNORORORVREFErrorAmpVREFOSCOUTTo InternalCircutryUVLOLockoutFlipFlopPWMLatch3 kW5 kWUC1527AOutput StageUC1525AOutput StageUC1525A, UC1527AUC2525A, UC2527AUC3525A, UC3527ASLUS191C – FEBRUARY 1997 – REVISED JANUARY 2008www.ti.comREGULATING PULSE WIDTH MODULATORS• 8-V to 35-V Operation• 5.1-V Reference Trimmed to 1%The UC1525A/1527A series of pulse width modulatorintegrated circuits are designed to offer improved• 100-Hz to 500-kHz Oscillator Rangeperformance and lowered external parts count when• Separate Oscillator Sync Terminalused in designing all types of switching power• Adjustable Deadtime Controlsupplies. The on-chip +5.1-V reference is trimmed to1% and the input common-mode range of the error• Internal Soft-Startamplifier includes the reference voltage, eliminating• Pulse-by-Pulse Shutdownexternal resistors. A sync input to the oscillator allows• Input Undervoltage Lockout With Hysteresismultiple units to be slaved or a single unit to besynchronized to an external system clock. A single• Latching PWM to Prevent Multiple Pulsesresistor between the CTand the discharge terminals• Dual Source/Sink Output Driversprovides a wide range of dead-time adjustment.These devices also feature built-in soft-start circuitrywith only an external timing capacitor required. Ashutdown terminal controls both the soft-start circuitryand the output stages, providing instantaneous turnoff through the PWM latch with pulsed shutdown, aswell as soft-start recycle with longer shutdowncommands.1Please be aware that an important notice concerning availability, standard warranty, and use in critical applications ofTexas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.PRODUCTION DATA information is current as of publication date.Copyright © 1997 – 2008, Texas Instruments IncorporatedProducts conform to specifications per the terms of the TexasInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.www.ti.comDESCRIPTION (continued)ABSOLUTE MAXIMUM RATINGS(1)RECOMMENDED OPERATING CONDITIONS(1)UC1525A, UC1527AUC2525A, UC2527AUC3525A, UC3527ASLUS191C – FEBRUARY 1997 – REVISED JANUARY 2008These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foamduring storage or handling to prevent electrostatic damage to the MOS gates.These functions are also controlled by an undervoltage lockout which keeps the outputs off and the soft-startcapacitor discharged for sub-normal input voltages. This lockout circuitry includes approximately 500 mV ofhysteresis for jitter- free operation. Another feature of these PWM circuits is a latch following the comparator.Once a PWM pulse has been terminated for any reason, the outputs will remain off for the duration of the period.The latch is reset with each clock pulse. The output stages are totem-pole designs capable of sourcing or sinkingin excess of 200 mA. The UC1525A output stage features NOR logic, giving a LOW output for an OFF state. TheUC1527A utilizes OR logic which results in a HIGH output level when OFF.UCx52xA UNIT+VINSupply voltage 40VCCollector supply voltage 40VLogic inputs – 0.3 to +5.5Analog inputs – 0.3 to +VINOutput current, source or sink 500Reference output current 50 mAOscillator charging current 5Power dissipation at TA= +25 ° C(2)1000mWPower dissipation at TC= +25 ° C(2)2000Operating junction temperature – 55 to 150Storage temperature range – 65 to 150 ° CLead temperature (soldering, 10 seconds) 300(1) Values beyond which damage may occur.(2) See Thermal Characteristics table.MIN MAX UNIT+VINInput voltage 8 35VVCCollector supply voltage 4.5 35Sink/source load current (steady state) 0 100Sink/source load current (peak) 0 400 mAReference load current 0 20Oscillator frequency range 100 400 HzOscillator timing resistor 2 150 k ΩOscillator timing capacitorm 0.001 0.01 µ FDead time resistor range 0 500 ΩUC1525A, UC1527A – 55 125Operating ambient temperature range UC2525A, UC2527A – 25 85 ° CUC3525A, UC3527A 0 70(1) Range over which the device is functional and parameter limits are assured.2 Submit Documentation Feedback Copyright © 1997 – 2008, Texas Instruments IncorporatedProduct Folder Link(s): UC1525A, UC1527A UC2525A, UC2527A UC3525A, UC3527Awww.ti.comTHERMAL CHARACTERISTICSCONNECTION DIAGRAMS1234 5678161514131211109INV InputNI InputSYNCOSC OutputCTRTDischargeSoft StartVREF+VINOutput BVCGroundOutput AShutdownCompensationJ or N PACKAGE(TOP VIEW)3 2 1 20 199 10 11 12 13456781817161514Output BVCNCGroundOutput ASYNCOSC OutputNCCTRTQ AND L PACKAGES(TOP VIEW)NI InputINV InputNCCompensationShutdownV+VDischargeSoft StartNCINREFNC − No internal connectionUC1525A, UC1527AUC2525A, UC2527AUC3525A, UC3527ASLUS191C – FEBRUARY 1997 – REVISED JANUARY 2008over operating free-air temperature range (unless otherwise noted)PACKAGE θJAθJCJ-16 80-120 28N-16 90 45DW-16 45-90 25PLCC-20 43-75 34LCC-20 70-80 20PLCC-20, LCC-20DIL-16Copyright © 1997 – 2008, Texas Instruments Incorporated Submit Documentation Feedback 3Product Folder Link(s): UC1525A, UC1527A UC2525A, UC2527A UC3525A, UC3527Awww.ti.comELECTRICAL CHARACTERISTICSf +1CTǒ0.7RT) 3RDǓUC1525A, UC1527AUC2525A, UC2527AUC3525A, UC3527ASLUS191C – FEBRUARY 1997 – REVISED JANUARY 2008+VIN= 20 V, and over operating temperature, unless otherwise specified, TA= TJPARAMETER TEST CONDITIONS MIN TYP MAX UNITREFERENCEUC152xA, UC252xA 5.05 5.10 5.15Output voltage TJ= 25 ° C VUC352xA 5.0 5.1 5.2Line regulationg VIN= 8 V to 35 V 10 20Load regulationg IL= 0 mA to 20 mA 20 50 mVTemperature stability(1)Over operating range 20 50UC152xA, UC252xA 5.0 5.2Total output variation(1)Line, load, and temperature VUC352xA 4.95 5.25Shorter circuit current VREF= 0, TJ= 25 ° C 80 100 mAOutput noise Voltage(1)10 Hz ≤ 10 kHz, TJ= 25 ° C 40 200 µ VrmsLong term stability(1)TJ= 125 ° C 20 50 mVOSCILLATOR SECTION(2)Initial accuracy(1) (2)TJ= 25 ° C 2%
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