LTC3765 Active Clamp Forward Controller and Gate Driver FEATURES DESCRIPTION n Supports Self-Starting Secondary-Side Control The LTC 3765 is a start-up controller and gate driver for n Direct Flux Limit Guarantees No Saturation use in a self-starting secondary-side control forward con- n Active Clamp Drive with Delay Adjustment verter. When combined with the LTC3766 secondary-side n On-Chip Bridge Rectifier Eliminates Need for synchronous forward controller, a complete isolated power Separate Gate Drive Bias Supply supply is created using a minimum of discrete parts. A n Wide Input Supply Range: 8V and Up (Limited Only proprietary scheme is used to multiplex gate drive signals by External Components) and bias power across the isolation barrier through a n Linear Regulator Controller for Fast Start-Up small pulse transformer. The LTC3765 contains an on- n High Speed Gate Drivers chip bridge rectifier that extracts gate drive bias power n Precision UVLO with Adjustable Hysteresis from this pulse transformer, eliminating the need for a n Overcurrent Protection separate bias supply. A precision undervoltage lockout n Overtemperature Protection circuit and linear regulator controller ensure a quick and n Adjustable Start-Up Frequency and Soft-Start well-controlled start-up. n Tiny 16-Lead MSOP Package The LTC3765 includes an active clamp output for driving an external PMOS, as well as an adjustable delay to optimize APPLICATIONS efficiency. The active clamp architecture reduces voltage stress on the main power switch, and provides the highest n Isolated Battery Chargers possible efficiency. Overcurrent protection and the Direct n Isolated 48V Telecommunication Systems Flux Limit guarantee no transformer saturation without n Servers and Embedded Computing compromising transient response. n Automotive and Heavy Equipment L, LT, LTC, LTM, PolyPhase, Linear Technology and the Linear logo are registered trademarks and Direct Flux Limit is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7200014 and 6144194. Other patents pending. TYPICAL APPLICATION 36V-72V to 5V/15A Active Clamp Isolated Forward Converter + T1 V + OUT V IN 6:2 5V 36V TO 72V L1 15A 1.4H 2.2F 220F L1: PULSE PA1393.152 100V 6.3V FDMS86201 BSC0901NS 33nF 100nF T1: PULSE PA0810 SiR414DP 3 2 200V 200V T2: PULSE PA0297 15m 3m 168 0.5W 2W V V IN OUT Si3437DV 2.2nF 100k 100 100 (SOT-23) 250VAC Si3440DV + 1nF 1 FG SW SG RUN V NDRV V FS/SYNC V V IN CC S S 4.42k I S 365k + + 0.1F 1.0F NDRV PG I I AG I S S T2 I FB 1/8W SMAG S + 2:1 + LTC3766 RUN IN PT ITH 604 LTC3765 PT V CC IN SS SSFLT FS/UV 470pF 4.7F GND PGND I SGD FGD MODE PK R DELAY SGND PGND CORE 33nF 26.1k 15k 22k 47pF 17.8k 33nF 15k 10.5k 14k 18.2k 3765 TA01 3765fa 1LTC3765 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V , NDRV Voltages ................................... 0.3V to 15V CC 1 PGND 16 IN (NDRV-V ) Voltage ..................................... 0.3V to 6V + CC PG 2 15 IN + 3 V 14 NDRV CC IN , IN , SSFLT Voltages ............................ 0.3V to 15V AG 4 17 13 SSFLT 5 I SGND 12 RUN SMAG I Voltage ................................................ 5V to 18V SMAG DELAY 6 11 R CORE 7 I 10 FS/UV RUN Voltage................................................0.3V to 12V S + I 8 9 SGND S + DELAY, R , FS/UV, I , I Voltages ....... 0.3V to 6V CORE S S MSE PACKAGE 16-LEAD PLASTIC MSOP Operating Junction Temperature Range (Notes 2, 3) T = 150C, = 45C/W, = 10C/W JMAX JA JC LTC3765E,LTC3765I .......................... 40C to 125C EXPOSED PAD (PIN 17) IS SGND, MUST BE SOLDERED TO PCB LTC3765H .......................................... 40C to 150C LTC3765MP ....................................... 55C to 150C 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 LTC3765EMSE PBF LTC3765EMSE TRPBF 3765 16-Lead Plastic MSOP 40C to 125C LTC3765IMSE PBF LTC3765IMSE TRPBF 3765 16-Lead Plastic MSOP 40C to 125C LTC3765HMSE PBF LTC3765HMSE TRPBF 3765 16-Lead Plastic MSOP 40C to 150C LTC3765MPMSE PBF LTC3765MPMSE TRPBF 3765 16-Lead Plastic MSOP 55C to 150C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: