Green phase-shifted full-bridge controller with SR control for Wide input voltage Range


Product details


Topology Phase-Shifted Full-Bridge Control method Current, Peak Current Mode, Voltage VCC (Min) (V) 8 VCC (Max) (V) 17 Duty cycle (Max) (%) 97 UVLO thresholds on/off (V) 7.3/6.7 Frequency (Max) (kHz) 1000 Operating temperature range (C) -40 to 125 Gate drive (Typ) (A) 0.2 Features Adjustable Switching Frequency, Current Limiting, Enable/Shutdown, Error Amplifier, Green Mode, Light Load Efficiency, Programmable Slope Compensation, Soft Start, Soft Switching, Synchronization Pin, Thermal Shutdown Rating Catalog open-in-new Find other PWM controllers & resonant controllers

Package | Pins | Size

TSSOP (PW) 24 34 mm² 7.7 x 4.4 open-in-new Find other PWM controllers & resonant controllers


  • Enhanced Zero-Voltage Switching (ZVS) Range
  • 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 Bidirectional Synchronization
  • (±3%) Cycle-by-Cycle Current Limit Protection With Hiccup Mode Support
  • 150-µA Start-Up Current
  • VDD Undervoltage Lockout
  • Wide Temperature Range: –40°C to +125°C

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The UCC28951 device is an enhanced version of the UCC28950. It is a fully compatible drop-in replacement for the UCC28950. Refer to application note SLUA853 to determine which controller to use. The UCC28951 uses advanced control of the full-bridge in addition to active control of the synchronous rectifier (SR) output stage.

Programmable delays ensure ZVS operation over a wide range of operating conditions, while the load current naturally tunes the switching delays of the secondary-side synchronous rectifiers(SR). This functionality maximizes overall system efficiency.

The UCC28951 has many light-load management features including burst-mode operation and dynamic SR ON and OFF control during transition into and out of discontinuous current mode (DCM) operation. The device operates in current-mode or voltage-mode control. The switching frequency can be programmed up to 1 MHz. The device has protection features including cycle-by-cycle current limit, UVLO, and thermal shutdown.

The 24-pin, TSSOP package complies with RoHS requirements .

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Technical documentation

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Type Title Date
* Data sheet UCC28951 Phase-Shifted Full-Bridge Controller for Wide Input-Voltage Range Applications datasheet Mar. 26, 2018
Application note Making the Correct Choice: UCC28950-Q1 or UCC28951-Q1 Nov. 13, 2017
User guide Using the UCC27714EVM-551 for Evaluating the UCC28951-Q1 Oct. 06, 2016
More literature Design review of a 2-kW parallelable power supply module Aug. 17, 2016
More literature Design review of a 2-kW parallelable power supply module (PPT) Aug. 17, 2016

Design & development

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Hardware development

document-generic User guide

This 600W EVM was designed to demonstrate how the UCC28950 control IC, UCC27524A and UCC27714 gate drivers could be used in a phase shifted full bridge converter that achieves ZVS from 50 to 100% load. 

  • ZVS from 50 to 100% load
  • Example of High efficiency design for 80 + Applications
  • Burst mode/DCM Function to reduce no load power dissipation to meet green mode requirements

Design tools & simulation

SLUM169B.ZIP (153 KB) - PSpice Model
SLUM276A.TSC (738 KB) - TINA-TI Reference Design
SLUM277A.TSC (739 KB) - TINA-TI Reference Design
SLUM278A.ZIP (98 KB) - TINA-TI Spice Model

Reference designs

2-kW industrial AC/DC battery charger reference design with 92% full-load efficiency
PMP8740 — This reference design is a module that can be set as standard power supply or a battery charger. The output voltage ranges from 0 V to 32 V at a maximum current of 62.5 A. It consists of four boards, a boost PFC, a phase shift full bridge, a small daughter board (hosting the microcontroller), and a (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

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TSSOP (PW) 24 View options

Ordering & quality

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