Datasheet LTC3765 (Analog Devices)

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 control er, 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 + VOUT IN 6:2 36V TO 72V 5V • • L1 15A 1.4µH 2.2µF L1: PULSE PA1393.152 220µF 100V FDMS86201 33nF 100nF BSC0901NS T1: PULSE PA0810 6.3V SiR414DP ×3 200V 200V T2: PULSE PA0297 ×2 15mΩ 3mΩ 168Ω 0.5W 2W V – – IN VOUT Si3437DV 2.2nF 100k (SOT-23) 100Ω 100Ω Si3440DV 250VAC 1Ω 1nF FG SW SG RUN V + – IN NDRV VCC FS/SYNC VS VS 4.42k I – S 365k NDRV PG I + I – AG I 0.1µF 1/8W S S SMAG T2 1.0µF I + S FB RUN IN+ 2:1 PT+ LTC3766 ITH 604Ω • • V LTC3765 PT– CC IN– SS SSFLT FS/UV 4.7µF GND PGND I 470pF PK SGD FGD MODE RCORE DELAY SGND PGND 33nF 26.1k 15k 22k 47pF 17.8k 15k 33nF 10.5k 14k 18.2k 3765 TA01 3765fb For more information www.linear.com/LTC3765 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Timing Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts