Low-Cost CVCC Flyback controller With primary-side regulation for bipolar Power Device


Product details


Control method Primary-side regulation Duty cycle (Max) (%) 99 Frequency (Max) (kHz) 80 UVLO thresholds on/off (V) 21/7.7 Features PSR, DCM, Soft Start, Low Power, Current Limiting, Cable Compensation 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


  • < 50-mW No-Load Power
  • Primary-Side Regulation (PSR) Eliminates Opto-
  • Dynamic BJT Drive
  • ± 5% Voltage and Current Regulation Across Line
    and Load
  • 80-kHz Maximum Switching Frequency Enables
    High-Power Density Charger Designs
  • Quasi-Resonant Valley-Switching Operation for
    Highest Overall Efficiency
  • Wide VDD Range Allows Small Bias Capacitor
  • Output Overvoltage, Low-Line, and Overcurrent
    Protection Functions
  • Programmable Cable Compensation
  • SOT23-6 Package
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The UCC28722 flyback power supply controller provides isolated-output constant-voltage (CV) and constant-current (CC) output regulation without the use of an optical coupler. The device processes information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current.

Dynamically-controlled operating states and a tailored modulation profile support high-efficiency operation at all load levels without sacrificing output transient response.

Control algorithms in the UCC28722 device allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a bipolar transistor power switch, enabling lower-cost converter design. Discontinuous conduction mode (DCM) with valley switching reduces switching losses, while 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. Output overvoltage and overcurrent as well as input undervoltage protection features help keep primary and secondary component stresses in check. The UCC28722 also allows compensation for voltage drop in the cable to be programmed with an external resistor.

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Technical documentation

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Type Title Date
* Data sheet UCC28722 Constant-Voltage, Constant-Current Controller With Primary-Side Regulation, BJT Drive datasheet (Rev. B) Oct. 30, 2015
Application note Common-Mode-Chokeless Bias Supply Reference Design Example Jan. 02, 2020
Application note Minimize Standby Consumption for UCC287XX Family Aug. 01, 2019
Application note Selecting Electrolitic Bus Capacitor for Universal Input Jul. 17, 2018
Application note Maximum Output Power and Thermal Considerations for UCC28720 and UCC28722 Dec. 06, 2017
Application note AC-DC Non-Isolated SMPS for Single-Phase Smart Meters Based on UCC28722 (Rev. A) Nov. 02, 2017
Technical article Making smart meter eFuses robust and reliable Jun. 28, 2017
Technical article Powering the IoT Jan. 26, 2017
Technical article A mini data concentrator for the smart grid Nov. 21, 2016
Application note Troubleshooting TI PSR controllers Oct. 03, 2016
Technical article Solving the biggest challenges when designing smart meter power supplies Sep. 06, 2016
Application note UCC28722, Bias Supply Design Considerations for Intelligent eMeter Applications Aug. 05, 2016
Application note Versatile Buck-Boost driver based on UCC28722 for 5W-9W LED Bulb Dec. 08, 2015
White paper Control Challenges for Low Power AC/DC Converters Oct. 02, 2015
White paper Control Challenges for Low Power AC/DC Converters (PPT) Oct. 02, 2015
Application note 5-W USB Flyback Design Example Using the UCC28722 Jan. 08, 2014

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 UCC28720EVM-212 is a 5W evaluation module for evaluating an off line adapter for USB applications. It is intended for evaluation purposes and is not intended to be an end product. The UCC28720EVM-212 converters 100V to 240V RMS input voltage down to 5V DC, with a 1A current limit for USB adapter (...)
  • <10mW no load power
  • Primary Side Regulation (PSR) eliminates opto-coupler
  • +/- 5% Voltage & Current Regulation
  • Quasi-resonant valley switching operation for highest overall efficiency
  • Wide VDD range (35V) allows small bias capacitor
  • Drive Output for low cost Bipolar
  • Protection Functions: Over Voltage, Low (...)

Design tools & simulation

SLUM466A.ZIP (64 KB) - PSpice Model
SLUC528A.ZIP (2330 KB)
SLUC529.ZIP (44 KB)

Reference designs

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CAD/CAE symbols

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SOT-23 (DBV) 6 View options

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