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Application Report
SLUA737B–March 2015–Revised October 2015
Using UCD7138 and UCD3138A for Advanced
Synchronous Rectification Control
ABSTRACT
The UCD7138 low-side MOSFET driver is a high-performance driver for secondary-side synchronous
rectification (SR), with body-diode conduction sensing. The device is suitable for high-power, high-
efficiency, isolated-converter applications requiring dead-time optimization. The UCD7138 gate driver is a
companion device to the UCD3138A, a highly-integrated digital controller for isolated power. The
UCD3138A has an advanced dead time control interface which accepts UCD7138 output signals and
optimizes SR gate driver signals accordingly. This application report provides the setup guide for
advanced synchronous rectification control of the two devices. The hardware connection, layout example,
and firmware example are provided.
Topic ........................................................................................................................... Page
1 Introduction ........................................................................................................ 2
2 Hardware Connection........................................................................................... 6
3 UCD7138 Layout Example..................................................................................... 9
4 UCD3138A Dead Time Compensation (DTC) Interface............................................. 12
5 Code Example.................................................................................................... 15
6 Register List ...................................................................................................... 17
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SLUA737B–March 2015–Revised October 2015 Using UCD7138 and UCD3138A for Advanced Synchronous Rectification
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