SLUSD90E June   2019  – February 2021 UCC256402 , UCC256403 , UCC256404


  1. Features
  2. Applications
  3. Description
  4. Revision History
    1.     Device Comparison Table
  5. Pin Configuration and Functions
    1.     Pin Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Hybrid Hysteretic Control
      2. 7.3.2 Regulated 13-V Supply
      3. 7.3.3 Feedback Chain
        1. Optocoupler Feedback Signal Input and Bias
        2. FB Pin Voltage Clamp
        3. "Pick Lower Value" Block and Soft Start Multiplexer
        4. Pick Higher Block and Burst Mode Multiplexer
        5. VCR Comparators
      4. 7.3.4 Resonant Capacitor Voltage Sensing
      5. 7.3.5 Resonant Current Sensing
      6. 7.3.6 Bulk Voltage Sensing
      7. 7.3.7 Output Voltage Sensing
      8. 7.3.8 High Voltage Gate Driver
        1. Adaptive Dead Time Control
      9. 7.3.9 Protections
        1. ZCS Region Prevention
        2. Over Current Protection (OCP)
        3. Bias Winding Over Voltage Protection (BWOVP)
        4. Input Under Voltage Protection (VINUVP)
        5. Input Over Voltage Protection (VINOVP)
        6. Boot UVLO
        7. RVCC UVLO
        8. Over Temperature Protection (OTP)
    4. 7.4 Device Functional Modes
      1. 7.4.1 High Voltage Start-Up
      2. 7.4.2 X-Capacitor Discharge
      3. 7.4.3 Burst Mode Control
        1. Soft-Start and Burst-Mode Threshold
        2. BMTL/BMTH Ratio Programming
      4. 7.4.4 System State Machine
  8. Power Supply Recommendations
    1. 8.1 VCC Pin Capacitor
    2. 8.2 Boot Capacitor
    3. 8.3 RVCC Pin Capacitor
  9. Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Related Links
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Community Resources
    5. 10.5 Trademarks

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Pin Functions

BLK4IThis pin is used to sense the LLC stage input voltage level. A resistor divider should be used to attenuate the signal before it is applied to this pin. The voltage level on this pin will determine when the LLC converter starts/stops switching.
BW8IThis pin is used to sense the output voltage through the bias winding. The sensed voltage is used for output over voltage protection. During startup, the pin is also used to program the ratio between the two burst mode thresholds (BMTL and BMTH).
FB5ILLC stage control feedback input. The amount of current sourced from this pin will determine the LLC input power level.
GND11GGround reference for all signals.
HB14IHigh-side gate-drive floating supply voltage. The bootstrap capacitor is connected between this pin and HS pin. A high voltage, high speed diode should be connected from RVCC to this pin to supply power to the high-side gate-driver during the period when the low-side MOSFET is conducting.
HO15OHigh-side floating gate-drive output.
HS16IHigh-side gate-drive floating ground. Current return for the high-side gate-drive current.
HV1IConnects to internal HV startup JFET. For UCC256402 and UCC256404, this pin provides start up power for both PFC and LLC stage. This pin also monitors the AC line voltage for x-capacitor discharge function. For UCC256403, this pin needs to be connected to ground.
ISNS6IResonant current sense. The resonant capacitor voltage is differentiated with a first order filter to measure the resonant current.
LL/SS9IThe capacitance value connected from this pin to ground will impact the duration of the soft-start period. The resistor divider connected to the pin will define the initial voltage applied on the pin for startup. After system startup, this pin is used to program the burst mode threshold.
LO10OLow-side gate-drive output.
Removed2N/AFunctional creepage and clearance
Removed13N/AFunctional creepage and clearance
RVCC12PRegulated 13-V supply. This pin is used to supply the gate driver and PFC controller.
VCC3PSupply input.
VCR7IResonant capacitor voltage sense.