UCC28720

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Constant-voltage, constant-current controller with primary-side regulation for bipolar power devices

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Product details

Parameters

Control method Primary-side regulation Duty cycle (Max) (%) 99 Frequency (Max) (kHz) 80 UVLO thresholds on/off (V) 21/7.7 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 open-in-new Find other Flyback controllers

Package | Pins | Size

SOIC (D) 7 29 mm² 4.9 x 6 open-in-new Find other Flyback controllers

Features

  • < 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
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Description

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
* Datasheet UCC28720 Constant-Voltage, Constant-Current Controller With Primary-Side Regulation datasheet (Rev. B) Sep. 30, 2015
Application notes Minimize Standby Consumption for UCC287XX Family Aug. 01, 2019
Application notes Maximum Output Power and Thermal Considerations for UCC28720 and UCC28722 Dec. 06, 2017
Application notes Troubleshooting TI PSR controllers Oct. 03, 2016
Technical articles Slim down your flyback; lose that excess snubber Feb. 15, 2016
White papers Control Challenges for Low Power AC/DC Converters Oct. 02, 2015
White papers Control Challenges for Low Power AC/DC Converters (PPT) Oct. 02, 2015
Technical articles Designing multiple output converters with primary side sensing Aug. 04, 2015
Application notes 5-W USB Flyback Design Example Using the UCC28722 Jan. 08, 2014
Technical articles Isolated power supplies – Is analog dead? Sep. 24, 2013
User guides Using the UCC28720EVM-212 (Rev. A) Sep. 20, 2013

Design & development

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

Hardware development

EVALUATION BOARDS Download
document-generic User guide
49
Description
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 (...)
Features
  • <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

CALCULATION TOOLS Download
SLUC528A.ZIP (2330 KB)
CALCULATION TOOLS Download
SLUC529.ZIP (44 KB)

Reference designs

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CAD/CAE symbols

Package Pins Download
SOIC (D) 7 View options

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