UCD7138 4-A and 6-A Single-Channel Synchronous-Rectifier Driver With Body-Diode Conduction Sensing and Reporting
1 Features
- Low-Side Gate Driver With Body-Diode Conduction Sensing
- Gate Turnoff Edge Body-Diode Conduction Reporting
- Gate Turnon Edge Delay Optimization
- 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.
Device Information(1)
| PART NUMBER | PACKAGE | BODY SIZE (NOM) |
|---|---|---|
| UCD7138 | WSON (6) | 3.00 mm × 3.00 mm |
- For all available packages, see the orderable addendum at the end of the datasheet.
4 Simplified Schematic
Power Savings for a 340-W LLC Application
5 Revision History
Changes from A Revision (April 2015) to B Revision
- Changed the device status from Product Preview to Production DataGo
6 Pin Configuration and Functions
Pin Functions
| PIN | TYPE | DESCRIPTION | |
|---|---|---|---|
| NO. | NAME | ||
| 1 | IN | I | Input: Gate driver input. This pin should be connected directly to the DPWM output of the digital controller. |
| 2 | DTC | O | Body-diode conduction-time report: Standard digital IO. Pulled high internally. Output low when the body diode is conducting. This pin should be connected to the DTC0 or DTC1 pin on UCD3138A. |
| 3 | VCC | P | IC supply: External bias supply input. The supply range is 4.5-V to 18-V. A ceramic bypass capacitor of at least 1 µF should be placed as close as possible to the VCC pin and the thermal pad. Where possible, use thick & wide Cu connections. |
| 4 | OUT | O | Gate driver output: Integrated push-pull gate driver for one or more external power MOSFETs. Typical 4-A source and 6-A sink capability. This is a rail-to-rail output, with the rails defined by the voltages on VCC and GND. This pin should be connected to the gate terminal of the synchronous rectification MOSFET. |
| 5 | VD | I | Drain voltage: Connect this pin as close as possible to the controlled-MOSFET drain pad. This pin is internally connected to the diode conduction detection comparator. The comparator has a –0.15-V threshold to detect body-diode conduction. A 20-Ω resistor should be connected between the VD pin and MOSFET drain terminal to limit the current. The maximum voltage of the VD pin should not exceed 45 V. A simple external circuit can enable the usage of much higher voltages, see Figure 34. |
| 6 | CTRL | I | Rising edge optimization control: Connect this pin to ground to disable rising edge optimization. Leave this pin floating or connect it to logic high to enable rising edge optimization. |
| — | Thermal Pad (GND) | — | Exposed thermal pad: The exposed pad on the bottom of the package enhances the thermal performance of the device. This pad is the device ground reference. |
