LTC3721-1 Push-Pull PWM Controller FEATURES DESCRIPTIO High Efficiency Push-Pull PWM The LTC 3721-1 push-pull PWM controller provides all of 1.5A Sink, 1A Source Output Drivers the control and protection functions necessary for com- Adjustable Push-Pull Dead-Time pact and highly efficient, isolated power converters. High Adjustable System Undervoltage Lockout and integration minimizes external component count, while Hysteresis preserving design flexibility. Adjustable Leading Edge Blanking The robust push-pull output stages switch at half the Low Start-Up and Quiescent Currents oscillator frequency. Dead-time is independently pro- Current Mode Operation grammed with an external resistor. A UVLO program input Single Resistor Slope Compensation provides precise system turn-on and turn off voltages. The V UVLO and 25mA Shunt Regulator CC LTC3721-1 features peak current mode control with pro- Programmable Fixed Frequency Operation to 1MHz grammable slope compensation and leading edge Soft-Start, Cycle-by-Cycle Current Limiting and blanking. Hiccup Mode Short-Circuit Protection The LTC3721-1 features extremely low operating and 5V, 15mA Low Dropout Regulator start-up currents and reliable short-circuit and 16-Pin SSOP and (4mm 4mm) QFN Packages overtemperature protection. The LTC3721-1 is offered in U 16-pin SSOP and (4mm 4mm) QFN packages. APPLICATIO S , LTC and LT are registered trademarks of Linear Technology Corporation. Telecommunications, Infrastructure Power Systems Distributed Power Architectures Server Power Supplies High Density Power Modules TYPICAL APPLICATIO Isolated Push-Pull Converter V IN V OUT + UVLO DRVA FROM AUXILIARY DRVB WINDING V CS CC DPRG R CS V LTC3721-1 REF C T V REF R LEB V OUT V OUT SS COMP + V R TOP COLL R REF LT1431 FB GND COMP R MID GND-F GND-S 37211 TA01 sn37211 37211fs 1 U ULTC3721-1 ABSOLUTE AXI U RATI GS (Note 1) V to GND (Low Impedance Source) .......0.3V to 10V V Output Current ............................... Self-Regulated CC REF (Chip Self-Regulates at 10.3V) Operating Temperature (Notes 5,6) UVLO to GND............................................. 0.3V to V LTC3721-1 ......................................... 40C to 85C CC All Other Pins to GND Storage Temperature Range ................. 65C to 125C (Low Impedance Source) .........................0.3V to 5.5V Lead Temperature (GN Package only) V (Current Fed) ................................................. 40mA (Soldering, 10sec) ............................................ 300C CC UUW PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART TOP VIEW ORDER PART V 1 16 NC NUMBER NUMBER REF NC 2 15 UVLO 16 15 14 13 LTC3721EGN-1 LTC3721EUF-1 NC 3 14 SS DRVB 1 12 FB DRVB 4 13 FB V 2 11 R CC LEB 17 V 5 12 R CC LEB DRVA 3 10 COMP DRVA 6 11 COMP PGND 4 9 CS GN PART UF PART GND 7 10 CS 5 6 7 8 MARKING MARKING C 8 9 DPRG T 37211 UF PACKAGE 37211 GN PACKAGE 16-LEAD (4mm 4mm) PLASTIC QFN 16-LEAD PLASTIC SSOP T = 125C, = 100C/W T = 125C, = 100C/W JMAX JA JMAX JA EXPOSED PAD IS GND (PIN17) MUST BE SOLDERED TO PCB Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 9.5V unless otherwise noted. A CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Input Supply V V Undervoltage Lockout Measured on V 10.25 10.7 V CCUV CC CC V V UVLO Hysteresis Measured on V 3.8 4.2 V CCHY CC CC I Start-Up Current V = V 0.3V 145 230 A CCST CC UVLO I Operating Current No Load on Outputs 3 6 mA CCRN V Shunt Regulator Voltage Current into V = 10mA 10.3 10.8 V SHUNT CC R Shunt Resistance Current into V = 10mA to 17mA 1.4 3.5 SHUNT CC SUVLO System UVLO Threshold Measured on UVLO Pin, 10mA into V 4.8 5.0 5.2 V CC SHYST System UVLO Hysteresis Current Current Flows Out of UVLO Pin, 10mA into V 8.5 10 11.5 A CC sn37211 37211fs 2 SGND NC C V T REF NC UVLO DPRG SS U WWW