POWER LOSS (W) LT3800 High-Voltage Synchronous Current Mode Step-Down Controller FEATURES DESCRIPTION n Wide 4V to 60V Input Voltage Range The LT 3800 is a 200kHz xed frequency high voltage n Output Voltages up to 36V synchronous current mode step-down switching regulator n Adaptive Nonoverlap Circuitry Prevents Switch controller. The IC drives standard gate N-channel power Shoot-Through MOSFETs and can operate with input voltages from 4V to n Reverse Inductor Current Inhibit for Discontinuous 60V. An onboard regulator provides IC power directly from Operation Improves Ef ciency with Light Loads V and provides for output-derived power to minimize IN n Output Slew Rate Controlled Soft-Start with V quiescent current. MOSFET drivers employ an internal IN Auto-Reset dynamic bootstrap feature, maximizing gate-source ON n 100A No Load Quiescent Current voltages during normal operation for improved operating n Low 10A Current Shutdown ef ciencies. The LT3800 incorporates Burst Mode opera- n 1% Regulation Accuracy tion, which reduces no load quiescent current to under n 200kHz Operating Frequency 100A. Light load ef ciencies are also improved through n Standard Gate N-Channel Power MOSFETs a reverse inductor current inhibit, allowing the controller n Current Limit Unaffected by Duty Cycle to support discontinuous operation. Both Burst Mode n Reverse Overcurrent Protection operation and the reverse-current inhibit features can be n 16-Lead Thermally Enhanced TSSOP Package disabled if desired. The LT3800 incorporates a program- mable soft-start that directly controls the voltage slew rate APPLICATIONS of the converter output for reduced startup surge currents and overshoot errors. The LT3800 is available in a 16-lead n 12V and 42V Automotive and Heavy Equipment thermally enhanced TSSOP package. n 48V Telecom Power Supplies L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks n Avionics and Industrial Control Systems and No R and ThinSOT are trademarks of Linear Technology Corporation. All other SENSE trademarks are the property of their respective owners. Protected by U.S. Patents including n Distributed Power Converters 5481178, 6611131, 6304066, 6498466, 6580258. TYPICAL APPLICATION 12V 75W DC/DC Converter with Reverse Current Inhibit and Input UVLO V IN Ef ciency and Power Loss 20V TO 55V + 1F 100 6 56F 3 2 V = 24V IN V BOOST IN V = 36V 1F 95 IN 5 Si7850DP 1M TG V = 60V LT3800 IN 82.5k 90 4 SHDN SW 1.5nF V = 48V BAS19 200k IN 85 3 C SS 15H 1N4148 174k BURST EN V 20k CC 80 2 1% 1% 1F LOSS (48V) Si7370DP V BG B160 FB 75 1 V PGND C 70 0 82.5k 100pF + 10 SENSE 0.1 1 SENSE SGND I (A) LOAD 680pF 0.015 3800 TA01b V OUT 12V AT 75W + 10F 270F 3800 TA01a 3800fc 1 EFFICIENCY (%)LT3800 ABSOLUTE MAXIMUM RATINGS (Note 1) PIN CONFIGURATION Supply Voltages TOP VIEW Input Supply Pin (V ) ............................... 0.3V to 65V IN V 1 16 BOOST IN Boosted Supply Pin (BOOST) .................... 0.3V to 80V NC 2 15 TG Boosted Supply Voltage (BOOST SW) ... 0.3V to 24V SHDN 3 14 SW Boosted Supply Reference Pin (SW) ............ 2V to 65V C 4 13 NC SS 17 Local Supply Pin (V ) .............................. 0.3V to 24V CC BURST EN 5 12 V CC Input Voltages V 6 11 BG FB + SENSE , SENSE ...................................... 0.3V to 40V V 7 10 PGND C + SENSE SENSE ......................................... 1V to 1V + SENSE 8 9 SENSE BURST EN Pin .......................................... 0.3V to 24V FE PACKAGE Other Inputs (SHDN, C , V , V ) .......... 0.3V to 5.0V SS FB C 16-LEAD PLASTIC TSSOP Input Currents T = 125C, = 40C/W, = 10C/W JMAX JA JC EXPOSED PAD (PIN 17) IS SGND SHDN, C ............................................... 1mA to 1mA SS MUST BE SOLDERED TO PCB Maximum Temperatures Operating Junction Temperature Range (Note 2) LT3800E (Note 3) .............................. 40C to 125C LT3800I ............................................. 40C to 125C Storage Temperature Range .................. 65C to 150C Lead Temperature (Soldering, 10 sec) ................. 300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT3800EFE PBF LT3800EFE TRPBF 3800EFE 16-Lead Plastic TSSOP 40C to 125C LT3800IFE PBF LT3800IFE TRPBF 3800IFE 16-Lead Plastic TSSOP 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: