UCC256303 (ACTIVE)

LLC Resonant Controller Enabling Low Standby Power



The UCC256303 is a fully featured LLC controller with integrated high-voltage gate driver. It has been designed to pair with a PFC stage to provide a complete power system using a minimum of external components. The resulting power system is designed to meet the most stringent requirements for standby power without the need for a separate standby power converter, and with PFC stage running all the time. UCC256303 includes a range of features designed to make LLC converter operation well controlled and robust. This device aims to unburden the LLC designer and allow mainstream applications to benefit from efficiency advantages of the LLC topology.

UCC256303 uses hybrid hysteretic control to provide best in class line and load transient response. The control effort is approximately linearly proportional to average input current in one cycle. The control makes the open loop transfer function a first order system so that it’s very easy to compensate. The system is always stable with proper frequency compensation.

UCC256303 provides a high efficient burst mode with consistent burst power level during each burst on cycle. The burst power level is programmable and adaptively changes with input voltage, making the optimization of efficiency very easy.


  • Hybrid Hysteretic Control (HHC)
    • Best-in-Class Transient Response
    • Easy Compensation Design
  • Optimized Low Power Features Enable 75 mW
    Standby Power Design with PFC on
    • Advanced Burst Mode
      Opto-Coupler Low Power Operation
    • Helps Enable Compliance to CoC Tier II Standard
  • Fast Exit from Burst Mode
  • Improved Capacitive Region Avoidance Scheme
  • Adaptive Dead-Time
  • Internal High-Side Gate Drivers
    (0.6-A and 1.2-A Capability)
  • Robust Soft Start with No Hard Switching
  • Over Temperature, Output Over Voltage, Input
    Over and Under Voltage Protection with
    Three Levels of Over Current Protections
  • Wide Operating Frequency Range
    (35 kHz to 1 MHz)
  • LLC Resonant Controller in SOIC16
    with High Voltage Clearance
  • External Bias Required
  • Create a Custom Design Using the UCC256303 With the WEBENCH® Power Designer

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Parametrics Compare all products in PWM and Resonant Controller

Control Method
Vin (Min) (V)
Vin (Max) (V)
Frequency (Max) (kHz)
Duty Cycle (Max) (%)
Gate Drive (Typ) (A)
Operating Temperature Range (C)
UCC256303 UCC25600 UCC256301 UCC256302 UCC256304
Resonant LLC   
Resonant LLC   
Resonant LLC   
Resonant LLC   
Resonant LLC   
Current    Voltage    Current    Current    Current   
600    410    600    600    600   
1000    350    1000    1000    1000   
50    50    50    50    50   
0.6    0.8    0.6    0.6    0.6   
Light Load Efficiency
Supports external bias
Thermal Shutdown   
  HV Start-up
Light Load Efficiency
Thermal Shutdown
Wide DC input
X cap discharge integrated   
HV Start-up
Light Load Efficiency
Thermal Shutdown   
HV Start-up
Light Load Efficiency
Thermal Shutdown
Wide AC input
Wide DC input
X cap discharge integrated   
Catalog    Catalog    Catalog    Catalog    Catalog   
-40 to 125    -40 to 125    -40 to 125    -40 to 125    -40 to 125   
14SOIC    8SOIC    14SOIC    14SOIC    14SOIC   

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WEBENCH® Designer UCC256303

  Min   Max Range
Vin  V 30.0 to 500.0V
Vout  V 5 to 400V
Iout  A ≤ 100A
Ambient Temp  °C -40 to 125°C

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