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UCC28950

Green Phase-Shifted Full-Bridge Controller With Synchronous Rectification

FEATURES

• Enhanced Wide Range Resonant Zero Voltage Switching (ZVS) Capability

• Direct Synchronous Rectifier (SR) Control

• Light-Load Efficiency Management Including

– Burst Mode Operation

– Discontinuous Conduction Mode (DCM), Dynamic SR On/Off Control with Programmable Threshold

– Programmable Adaptive Delay

• Average or Peak Current Mode Control with Programmable Slope Compensation and Voltage Mode Control

• Closed Loop Soft Start and Enable Function

• Programmable Switching Frequency up to 1 MHz with Bi-Directional Synchronization

• (+/-3%) Cycle-by-Cycle Current Limit Protection with Hiccup Mode Support

• 150-µA Start-Up Current

• V_DD Under Voltage Lockout

• Wide Temperature Range -40°C to 125°C

APPLICATIONS

• Phase-Shifted Full-Bridge Converters

• Server, Telecom Power Supplies

• Industrial Power Systems

• High-Density Power Architectures

• Solar Inverters, and Electric Vehicles

DESCRIPTION

The UCC28950 enhanced phase-shifted controller builds upon Texas Instrument’s industry standard UCCx895 phase-shifted controller family with enhancements that offer best in class efficiency in today’s high performance power systems. The UCC28950 implements advanced control of the full-bridge along with active control of the synchronous rectifier output stage.

The primary-side signals allow programmable delays to ensure ZVS operation over wide-load current and input voltage range, while the load current naturally tunes the secondary-side synchronous rectifiers switching delays, maximizing overall system efficiency.

The UCC28950 also offers multiple light-load management features including burst mode and dynamic SR on/off control when transitioning in and out of Discontinuous Current Mode (DCM) operation, ensuring ZVS operation is extended down to much lighter loads.

In addition, the UCC28950 includes support for peak current along with voltage mode control, programmable switching frequency up to 1 MHz and a wide set of protection features including cycle-by-cycle current limit, UVLO and thermal shutdown. A 90-degree phase-shifted interleaved synchronized operation can be easily arranged between two converters.

The UCC28950 is available in TSSOP-24 package.

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range (unless otherwise noted) ⁽¹⁾⁽²⁾

(1) Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) These devices are sensitive to electrostatic discharge; follow proper device handling procedures.

(3) All voltages are with respect to GND unless otherwise noted. Currents are positive into, negative out of the specified terminal. See Packaging Section of the datasheet for thermal limitations and considerations of packages.

UCC28950 Typical Application