High-Efficiency Flyback controller With Optocoupler Feedback


Product details


Control method Secondary-side regulation Duty cycle (Max) (%) 99 Frequency (Max) (kHz) 105 UVLO thresholds on/off (V) 22/7.7 Features SSR, DCM Operating temperature range (C) -40 to 125 Rating Catalog open-in-new Find other Flyback controllers

Package | Pins | Size

SOT-23 (DBV) 6 5 mm² 2.9 x 1.6 open-in-new Find other Flyback controllers


  • Opto-Coupled Feedback Enables up to 1% Regulation
  • Accurate Current Limit with Overload Timeout Protection and Delayed Hiccup Response
  • Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
  • 80-kHz Maximum Switching Frequency
  • Frequency Dithering to Ease EMI Compliance
  • Clamped Gate-Drive Output for MOSFET
  • Ultra-Low Start-Up Current and Large VDD Hysteresis
    • High Value Start-Up Resistor
    • Low Bias Capacitance
  • Fault Protections
    • Input Low Line
    • Output Over-Voltage
    • Over-Current
    • Short-Circuit
  • SOT23-6 Package
  • Create a Custom Design Using the UCC28742 with the WEBENCH® Power Designer

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The UCC28742 off-line flyback controller is a highly integrated, 6-pin secondary-side regulated PWM controller for efficient AC-to-DC power supplies. It is an isolated-flyback power-supply controller that provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. This device processes information from opto-coupled feedback and an auxiliary flyback winding for high-performance control of output voltage and current.

The UCC28742 employs advanced control algorithms to achieve high operating efficiency and performance. The drive output interfaces to a MOSFET power switch. Discontinuous conduction mode (DCM) with valley-switching reduces switching losses. Modulation of switching frequency and primary current-peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.

The controller has a maximum switching frequency of 80 kHz and always maintains control of the peak-primary current in the transformer. A minimum switching frequency of 200 Hz facilitates the achievement of low no-load input power.

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Technical documentation

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Type Title Date
* Datasheet UCC28742 High-Efficiency Flyback Controller with Optocoupler Feedback datasheet (Rev. A) May 08, 2018
Application notes Minimize Standby Consumption for UCC287XX Family Aug. 01, 2019
Technical articles Choosing the right flyback controller for your design Aug. 24, 2018
Application notes Selecting Electrolitic Bus Capacitor for Universal Input Jul. 17, 2018
User guides Using the UCC28742EVM-001 (Rev. B) Jun. 06, 2018

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

The UCC28742EVM-001 is a 10-W evaluation module for evaluating an off-line adapter for USB applications. The EVM meets CoC tier 2 and DoE Level 6 efficiency and standby power requirements. It is intended for evaluation purposes and is not intended to be an end product. The UCC28742EVM-001 converts (...)

  • Opto-coupled feedback for constant output voltage operation
  • Brick-wall current limit, with +/- 5% accuracy, and timeout delay hiccup, over current protection.
  • Enables +/- 1% output voltage regulation
  • Resonant valley switching for reduced switching losses and high effiency
  • Frequency dithering to reduce (...)

Design tools & simulation

SLUJ001A.ZIP (840 KB) - SIMPLIS Model
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PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
  • (...)
SLUC652B.ZIP (301 KB)

Reference designs

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CAD/CAE symbols

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SOT-23 (DBV) 6 View options

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