LT1737 - High Power Isolated Flyback Controller

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
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT1737 Typical Application

Description

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.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT1737CGN#PBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LT1737CGN#TRPBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LT1737CS#PBF SO-16 S C 05-08-1610 (S16) Yes
LT1737CS#TRPBF SO-16 S C 05-08-1610 (S16) Yes
LT1737IGN#PBF SSOP-16 GN I 05-08-1641 (GN16) Yes
LT1737IGN#TRPBF SSOP-16 GN I 05-08-1641 (GN16) Yes
LT1737IS#PBF SO-16 S I 05-08-1610 (S16) Yes
LT1737IS#TRPBF SO-16 S I 05-08-1610 (S16) Yes


LT1737 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT1737CGN#PBF SSOP-16 C $3.55 $3.00 Yes
LT1737CGN#TRPBF SSOP-16 C $3.06 Yes
LT1737CS#PBF SO-16 C $3.43 $2.90 Yes
LT1737CS#TRPBF SO-16 C $2.96 Yes
LT1737IGN#PBF SSOP-16 I $4.14 $3.50 Yes
LT1737IGN#TRPBF SSOP-16 I $3.56 Yes
LT1737IS#PBF SO-16 I $4.03 $3.40 Yes
LT1737IS#TRPBF SO-16 I $3.46 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC418A LT1737CS | Isolated, Triple Output Power Supply, Vin=8V to 36V, Vout=+15V @ 100mA, -15V @ 100mA, +5V @ 200mA $150.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT1737IGN#PBF SSOP-16 I $4.14 $3.50 Yes
LT1737IGN#TRPBF SSOP-16 I $3.56 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Applications

  • Isolated Flyback Switching Regulators
  • Medical Instruments
  • Instrumentation Power Supplies

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

Models for the following parts are available in LTspice:
LT1737

Technical Support