High-density flyback controller for active-clamp (ACF) and zero-voltage switching (ZVS) topologies


Product details


Control mode Secondary-side regulation Frequency (Max) (kHz) 1500 UVLO thresholds on/off (V) 2.2(ON)/1.23(OFF) Duty cycle (Max) (%) 99 Features Integrated Switching Bias Regulator, SSR, Zero Voltage Switching, OVP, Adaptive Burst Mode, X-Cap Discharge Operating temperature range (C) -40 to 125 Rating Catalog Device type Controllers Topology Flyback open-in-new Find other Flyback controllers

Package | Pins | Size

WQFN (RTW) 24 16 mm² 4 x 4 open-in-new Find other Flyback controllers


  • Active clamp recovers leakage inductance energy

  • Adaptive control for fast zero voltage switching (ZVS) tracking and dead time optimization

  • Integrated switching bias regulator supports USB Type-C PD wide output voltage range with one auxiliary winding
  • EMI frequency dithering without trade-offs on transient response or audible noise
  • Dynamic bias power management for digital isolator and GaN driver
  • Programmable Adaptive Burst Mode (ABM) with internal compensation
  • Active X-capacitor (X-cap) discharge
  • Over-temperature, over-voltage, output short-circuit, over-current, over-power, and pin-fault protections
  • Auto-recovery and group-latch fault options with fast latch-reset capability

  • 4x4-mm 24-pin QFN package

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The UCC28782 is a high-density active-clamp flyback (ACF) controller for USB Type C™ PD applications and allows for efficiencies over 93% by recovering the leakage inductance energy and adaptive ZVS tracking over the full load range.

With a maximum frequency of 1.5 MHz the magnetics can be minimized. Frequency dithering helps to improve EMI margin. The UCC28782 also integrates dynamic bias power management to optimize the gate drive for Si or GaN MOSFETs.

Adaptive Burst Mode (ABM) combined with Low Power Mode (LPM) and Standby Power mode (SBP) work together to increase light-load efficiency while reducing ripple and audible noise.

The UCC28782 also integrates an X-Cap discharge function to discharge the residual input voltage when power is removed.

The UCC28782 has multiple protection modes and options for retry or latch-off responses depending on the application needs. See Device Comparison Table.

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Technical documentation

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Type Title Date
* Data sheet UCC28782 High-Density Active-Clamp Flyback Controller with EMI Dithering, X-Cap Discharge, and Bias Power Management datasheet (Rev. D) May 20, 2021
Application note Transformer structures that achieve low EMI with low- and high-side rectifiers Sep. 22, 2020
User guide Using the UCC28782EVM-030 (Rev. B) Aug. 20, 2020
Certificate UCC28782EVM-030 EU Declaration of Conformity (DoC) (Rev. A) Jun. 29, 2020

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Hardware development

document-generic User guide
UCC28782EVM-030 demonstrates high-efficiency and high-density for a 65-W USB Type-C™ power delivery (PD) off-line adapter using the UCC28782 active-clamp flyback controller.  The input supports a universal 90 Vac to 264 Vac and the single output can be set to 5 V, 9 V and 15 V all at 3-A (...)
  • Universal AC input of 90 to 264 Vac with USB Type-C™ PD 3.0 compliant output up to 65 W (5 V/3 A, 9 V/3 A, 15 V /3 A, 20 V/3.25 A)
  • Efficiency and standby power consumption exceeds regulatory requirements CoC Tier 2 and DoE Level VI
  • Power density of 30 W/in3 with an efficiency of 93% at 90-VAC full (...)

Design tools & simulation

SLUM740.ZIP (617 KB) - SIMPLIS Model

Reference designs

65-W USB Type-C® ZVS-flyback reference design
PMP22322 — This reference design is a low-cost, high-density USB adapter that uses the UCC28782 active-clamp flyback controller and UCC5304 isolated driver in a ZVS-flyback topology. The maximum power rating is 65 W at 20-V output but is adjustable for 20-V/15-V/9-V/5-V output voltages and 3 A. This design (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

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WQFN (RTW) 24 View options

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