LTC3900 - Synchronous Rectifier Driver for Forward Converters

Features

  • N-Channel Synchronous Rectifier MOSFET Driver
  • Programmable Timeout Protection
  • Reverse Inductor Current Protection
  • Pulse Transformer Synchronization
  • Wide VCC Supply Range: 4.5V to 11V
  • 15ns Rise/Fall Times at VCC = 5V, CL = 4700pF
  • Undervoltage Lockout
  • Small SO-8 Package

Typical Application

LTC3900 Typical Application
LTC3900 Typical Application

Description

The LTC®3900 is a secondary-side synchronous rectifier driver designed to be used in isolated forward converter power supplies. The chip drives N-channel rectifier MOSFETs and accepts pulse sychronization from the primary-side controller via a pulse transformer.

The LTC3900 incorporates a full range of protection for the external MOSFETs. A programmable timeout function is included that disables both drivers when the synchronization signal is missing or incorrect. Additionally, the chip senses the output inductor current through the drainsource resistance of the catch MOSFET, shutting off the MOSFET if the inductor current reverses. The LTC3900 also shuts off the drivers if the supply voltage is too low.

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
LTC3900ES8#PBF SO-8 S8 E 05-08-1610 (S8) Yes
LTC3900ES8#TRPBF SO-8 S8 E 05-08-1610 (S8) Yes
LTC3900HS8#PBF SO-8 S8 H 05-08-1610 (S8) Yes
LTC3900HS8#TRPBF SO-8 S8 H 05-08-1610 (S8) Yes
LTC3900IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LTC3900IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes
LTC3900MPS8#PBF SO-8 S8 MP 05-08-1610 (S8) Yes
LTC3900MPS8#TRPBF SO-8 S8 MP 05-08-1610 (S8) Yes


LTC3900 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
LTC3900ES8#PBF SO-8 E $3.57 $2.50 Yes
LTC3900ES8#TRPBF SO-8 E $2.56 Yes
LTC3900HS8#PBF SO-8 H $4.11 $2.88 Yes
LTC3900HS8#TRPBF SO-8 H $2.94 Yes
LTC3900IS8#PBF SO-8 I $3.70 $2.59 Yes
LTC3900IS8#TRPBF SO-8 I $2.65 Yes
LTC3900MPS8#PBF SO-8 MP $10.00 $7.00 Yes
LTC3900MPS8#TRPBF SO-8 MP $7.06 Yes
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* 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
DC1317A-C LT1952EGN-1/LTC3900 Demo Board | Active Reset, Vin=18V-72V Vout=12V @ 10A $175.00
DC1317A-G LT1952EGN-1/LTC3900 Demo Board | Active Reset, Vin=9V-36V Vout=12V @ 5A $175.00
DC677A LT1952-1EGN-1, LTC3900ES Demo Board | Vin=36V-75V, Vout=3.3V @ 50A Contact Factory
DC968A-A LT1952EGN-1, LTC3900CS8, LT4430ES6 Demo Board | Vin=34V-75V Vout=3.3V @ 30A $150.00
DC968A-B LT1952EGN-1, LTC3900CS8, LT4430ES6 Demo Board | Vin=18V-36V, Vout=5V @ 20A $175.00
DC968A-C LT1952EGN-1, LTC3900CS8, LT4430ES6 Demo Board | Vin=36V-75V, Vout=12V @ 12A $150.00
DC968A-D LT1952EGN-1, LTC3900CS8, LT4430ES6 Demo Board | Vin=36V-75V, Vout=28V @ 4A $175.00
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Click here to view our complete list of demo boards

Applications

  • 48V Input Isolated DC/DC Converters
  • Isolated Telecom Power Supplies
  • High Voltage Distributed Power 
  • Step-Down Converters
  • Industrial Control System Power Supplies
  • Automotive and Heavy Equipment

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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

To launch a ready to run LTspice demonstration circuit for this part:

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Models for the following parts are available in LTspice:
LTC3900

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