Product details

Control mode Primary-side regulation Frequency (Max) (kHz) 80 UVLO thresholds on/off (V) 21/7.7 Duty cycle (Max) (%) 99 Features PSR, DCM, HV Start-up, Current Limiting, Green Mode, HV Start-up, Input Line Monitor, Leading Edge Blanking, Light Load Efficiency, Low Power, Soft Start Operating temperature range (C) -40 to 125 Rating Catalog Device type Controllers Topology Buck, Flyback
Control mode Primary-side regulation Frequency (Max) (kHz) 80 UVLO thresholds on/off (V) 21/7.7 Duty cycle (Max) (%) 99 Features PSR, DCM, HV Start-up, Current Limiting, Green Mode, HV Start-up, Input Line Monitor, Leading Edge Blanking, Light Load Efficiency, Low Power, Soft Start Operating temperature range (C) -40 to 125 Rating Catalog Device type Controllers Topology Buck, Flyback
SOIC (D) 7 29 mm² 4.9 x 6
  • < 10-mW No-Load Power
  • Primary-Side Regulation (PSR) Eliminates Opto-
    Coupler
  • ±5% Voltage and Current Regulation Across Line
    and Load
  • 700-V Start-Up Switch
  • 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
  • Dynamic BJT Drive
  • Overvoltage, Low-Line, and Overcurrent
    Protection Functions
  • Programmable Cable Compensation
  • SOIC-7 Package
  • < 10-mW No-Load Power
  • Primary-Side Regulation (PSR) Eliminates Opto-
    Coupler
  • ±5% Voltage and Current Regulation Across Line
    and Load
  • 700-V Start-Up Switch
  • 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
  • Dynamic BJT Drive
  • Overvoltage, Low-Line, and Overcurrent
    Protection Functions
  • Programmable Cable Compensation
  • SOIC-7 Package

The UCC28720 flyback power supply controller provides isolated-output Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current.

An internal 700-V start-up switch, dynamically-controlled operating states and a tailored modulation profile support ultra-low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28720 allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a bipolar transistor 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. Protection features help keep primary and secondary component stresses in check. The UCC28720 allows compensation for voltage drop in the cable to be programmed with an external resistor.

The UCC28720 flyback power supply controller provides isolated-output Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current.

An internal 700-V start-up switch, dynamically-controlled operating states and a tailored modulation profile support ultra-low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28720 allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a bipolar transistor 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. Protection features help keep primary and secondary component stresses in check. The UCC28720 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 UCC28720 Constant-Voltage, Constant-Current Controller With Primary-Side Regulation datasheet (Rev. B) 30 Sep 2015
Application note Flyback Aux Winding OVP and UVLO Fault Sensing Design and Troubleshooting Tips 31 Aug 2021
Application note Minimize Standby Consumption for UCC287XX Family 01 Aug 2019
Application note Maximum Output Power and Thermal Considerations for UCC28720 and UCC28722 06 Dec 2017
Application note Troubleshooting TI PSR controllers 03 Oct 2016
Technical article Slim down your flyback; lose that excess snubber 15 Feb 2016
White paper Control Challenges for Low Power AC/DC Converters 02 Oct 2015
White paper Control Challenges for Low Power AC/DC Converters (PPT) 02 Oct 2015
Technical article Designing multiple output converters with primary side sensing 04 Aug 2015
Application note 5-W USB Flyback Design Example Using the UCC28722 08 Jan 2014
Technical article Isolated power supplies – Is analog dead? 24 Sep 2013
User guide Using the UCC28720EVM-212 (Rev. A) 20 Sep 2013

Design & development

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Evaluation board

UCC28720EVM-212 — UCC28720EVM-212 5W Evaluation Module for USB off-line adapter

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 (...)
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Calculation tool

UCC28722 MathCad Design Tool (Rev. A)

SLUC528A.ZIP (2330 KB)
Calculation tool

UCC28722 Excel Design Tool

SLUC529.ZIP (44 KB)
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