1 Features
1• Low-Side Gate Driver With Body-Diode
Conduction Sensing
• Gate Turnoff Edge Body-Diode Conduction
Reporting synchronous•
Gate Turnon Edge Delay Optimization high•
Works Together With the Dead-Time
Compensation (DTC) Module in the UCD3138A
Family of Digital Power Controllers:
– Automatic or Manual Dead-Time Adjustment of
Gate Turnon and Turnoff Edges
– Negative Current Protection
• -150-mV Body-Diode Conduction Sensing
Threshold
• Able to Sense Body Diode Conduction Times as
Low as 10 ns
• 4-A Peak-Source and 6-A Peak-Sink Drive
Current
• Fast Propagation Delays (14-ns Typical)
• Fast Rise and Fall Times (5-ns Typical)
• Up to 2-MHz Operating Frequency
• 4.5-V to 18-V Supply Range
• Rail-to-Rail Drive Capability
• VCC Undervoltage Lockout (UVLO)
• 6-Pin 3-mm × 3-mm WSON-6 Package

2 Applications
• LLC Converters
• Hard Switching Full-Bridge Converters
• Digital Power-Control Applications

3 Description
The UCD7138 device is a 4-A and 6-A single-channel
MOSFET driver with body-diode conduction sensing
and reporting and is a high performance driver that
allows the Texas Instruments UCD3138A digital
PWM controller to achieve advanced synchronous•
rectification (SR) control. The device contains a high•
speed gate driver, a body-diode conduction-sensing
circuit, and a turnon delay optimization circuit. The
device is suitable for high-power, high-efficiency isolated converter applications where SR dead-time
optimization is desired.
The UCD7138 device offers asymmetrical rail-to-rail
4-A source and 6-A sink peak-current drive capability.
The short propagation delay and fast rise and fall
time allows efficient operation at high frequencies. An
internal high-speed comparator with a –150-mV
threshold detects the body-diode conduction and reports the information to the UCD3138A digital-
power controller. The UCD7138 device is capable of
sensing body-diode conduction time as low as 10 ns.
The SR turnon edge is optimized by the UCD7138
device. The SR turnoff edge is optimized by the UCD3138A digital-power controller which analyzes
the body-diode conduction information reported by
the UCD7138 DTC pin.
The benefits of the chipset include maximizing
system efficiency by minimizing body-diode
conduction time, robust and fast negative-current
protection, and a simple interface.