LT1737 - High Power Isolated Flyback Controller

The LT1737 is a monolithic switching regulator controller specifically designed for the isolated flyback topology. It drives the gate of an external MOSFET and is generally powered from a DC supply voltage. Output voltage feedback information may be supplied by a variety of methods including a third transformer winding, the primary winding or even direct DC feedback (see Applications Information). Its gate drive capability coupled with a suitable external MOSFET and other power path components can deliver load power up to tens of Watts.

The LT1737 has a number of features not found on other isolated flyback controller ICs presently available. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation. Its unique control circuitry can maintain regulation well into discontinuous mode in most applications. Optional load compensation circuitry allows for improved load regulation. An optional undervoltage lockout pin halts operation when the application input voltage is too low. An optional external capacitor implements a soft-start function.

Features
  • Drives External Power MOSFET
  • Supply Voltage Range: 4.5V to 20V
  • Flyback Voltage Limited Only by External Components
  • Senses Output Voltage Directly from Primary Side Winding—No Optoisolator Required
  • Moderate Accuracy Regulation Without User Trims
  • Regulation Maintained Well into Discontinuous Mode
  • Switching Frequency from 50kHz to 250kHz with External Capacitor
  • Available in 16-Pin GN and SO Packages
  • Optional Load Compensation
  • Optional Undervoltage Lockout
  • External ISENSE Resistor
  • Shutdown Feature Reduces IQ to 50µA Typ
Typical Application
Applications
  • Isolated Flyback Switching Regulators
  • Medical Instruments
  • Instrumentation Power Supplies
Packaging
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LT1737CGN#PBFSSOP-16C$3.55$3.00
LT1737CGN#TRPBFSSOP-16C$3.06
LT1737CS#PBFSO-16C$3.43$2.90
LT1737CS#TRPBFSO-16C$2.96
LT1737IGN#PBFSSOP-16I$4.14$3.50
LT1737IGN#TRPBFSSOP-16I$3.56
LT1737IS#PBFSO-16I$4.03$3.40
LT1737IS#TRPBFSO-16I$3.46
Demo Boards
Part NumberDescriptionPrice
DC418ALT1737CS | Isolated, Triple Output Power Supply, Vin=8V to 36V, Vout=+15V @ 100mA, -15V @ 100mA, +5V @ 200mA$150.00
Datasheet
Reliability Data
Related Product
LT1737 - High Power Isolated Flyback Controller
R387 Reliability Data
LT1737 Footprints and Symbols