UCC28951-Q1 (ACTIVE)

Phase-Shifted Full-Bridge Controller for Wide Input Voltage Range

Phase-Shifted Full-Bridge Controller for Wide Input Voltage Range  - UCC28951-Q1


The UCC28951-Q1 device is a new enhanced version of the UCC28950-Q1; it is a fully compatible drop-in replacement for the UCC28950-Q1. Reference application note Making the Correct Choice: UCC28950-Q1 or UCC28951-Q1 (SLUA853) for choosing the controller to best fit your application. The UCC28951-Q1 implements advanced control of the full-bridge along with 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 SRs, maximizing overall system efficiency.

The UCC28951-Q1 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.

In addition, the UCC28951-Q1 includes support for current or 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.

The UCC28951-Q1 is available in 24-pin TSSOP package and is RoHS compliant.


  • Qualified for Automotive Applications
  • AEC-Q100 Qualified With the Following Results:
    • Device Temperature Grade 1: –40ºC to +125ºC Ambient Operating Temperature Range
    • Device HBM ESD Classification Level H2
    • Device CDM ESD Classification Level C3B
  • 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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Parametrics Compare all products in PWM and Resonant Controller

Control Method
Vin (Min) (V)
Vin (Max) (V)
Frequency (Max) (kHz)
UVLO Thresholds On/Off (V)
Duty Cycle (Max) (%)
Gate Drive (Typ) (A)
Operating Temperature Range (C)
UCC28951-Q1 UCC2895-Q1 UCC28950-Q1
Phase-Shifted Full-Bridge    Phase-Shifted Full-Bridge    Phase-Shifted Full-Bridge   
Peak Current Mode
7.3    11    7.3   
20    17    20   
1000    1000    1000   
7.3/6.7    11/9    7.3/6.7   
97    100    97   
0.2    0.1    0.2   
Adjustable Switching Frequency
Current Limiting
Error Amplifier
Green Mode
Programmable Slope Compensation
Soft Start
Soft Switching
Synchronization Pin
Thermal Shutdown   
Adjustable Switching Frequency
Current Limiting   
Adjustable Switching Frequency
Current Limiting
Error Amplifier
Soft Start
Soft Switching   
Automotive    Automotive    Automotive   
-40 to 125    -40 to 125    -40 to 105
-40 to 125   
24TSSOP    20SOIC    24TSSOP