Constant-voltage, constant-current PWM with PSR, NTC option, and 300mV cable compensation


Product details


Control method Primary-side regulation Duty cycle (Max) (%) 99 Frequency (Max) (kHz) 132 UVLO thresholds on/off (V) 21/8.1 Features PSR, DCM Operating temperature range (C) -20 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


  • < 30-mW No-Load Power for 5-Star Rating
  • Primary-Side Regulation (PSR) Eliminates Opto-Coupler
  • ±5% Voltage and Current Regulation
  • 130-kHz Maximum Switching Frequency Enables High-Power
    Density Charger Designs
  • Quasi-Resonant Valley-Switching Operation for Highest
    Overall Efficiency
  • Patent-Pending Frequency-Jitter Scheme to Ease EMI
  • Wide VDD Range Allows Small Bias Capacitor
  • Clamped Gate-Drive Output for MOSFET
  • Protection Functions: Overvoltage, Low-Line, and
  • Programmable Cable Compensation (UCC28700 Only)
  • NTC Resistor Interface (UCC28701, UCC28702 and UCC28703
    Only) With Fixed Cable Compensation Options
  • SOT-23 Package
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The UCC28700 family of flyback power supply controllers provides 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. Low start-up current, dynamically controlled operating states and a tailored modulation profile support very low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28700 family allow operating efficiencies to meet or exceed applicable standards. The output drive 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 controllers have a maximum switching frequency of 130 kHz and always maintain control of the peak-primary current in the transformer. Protection features help keep primary and secondary component stresses in check. The UCC28700 allows the level of cable compensation to be programmed. The UCC28701, UCC28702, and UCC28703 devices allow remote temperature sensing using a Negative Temperature Coefficient (NTC) resistor while providing fixed cable-compensation levels.

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Same functionality and pinout but is not an equivalent to the compared device:
UCC28704 ACTIVE Off-lineconstant-voltage constant-current Flyback controller with primary-side regulation (PSR) This product is a newer PSR flyback controller with better performance and meets the latest energy efficiency standards. It is suggested for new designs.

Technical documentation

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Type Title Date
* Datasheet UCC2870x Constant-Voltage, Constant-Current Controller With Primary-Side Regulation datasheet (Rev. A) Dec. 12, 2014
Application notes Minimize Standby Consumption for UCC287XX Family Aug. 01, 2019
Application notes Selecting Electrolitic Bus Capacitor for Universal Input Jul. 17, 2018
Application notes Troubleshooting TI PSR controllers Oct. 03, 2016
Application notes Choosing Standard Recovery Diode or Ultra-Fast Diode in Snubber Oct. 09, 2015
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
Application notes UCC28700 5-W USB Flyback Design Review (Rev. C) Feb. 21, 2014
More literature Exposing the Inner Behavior of a Quasi-Resonant Flyback Converter Oct. 29, 2013

Design & development

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

Hardware development

UCC28700 evaluation module
document-generic User guide
The Texas Instruments UCC28700EVM-068 evaluation module (EVM) helps designers evaluate the performance of the UCC28700 Constant-Voltage, Constant-Current PWM with Primary-Side Regulation. The 5W EVM is used for evaluating an off line adapter for USB applications. It converts a 90V to 265V RMS input (...)
  • <30mW no load power for 5 star rating
  • Primary Side Regulation (PSR) eliminates opto-coupler
  • +/- 5% Voltage & Current Regulation
  • 130 KHz max. switching frequency enables high power density charger designs
  • Quasi-resonant valley switching operation for highest overall efficiency
  • Wide VDD range (35V) allows (...)

Design tools & simulation

SLUM455.ZIP (131 KB) - PSpice Model
SLUM617.ZIP (101 KB) - TINA-TI Spice Model
SLUM619.TSC (195 KB) - TINA-TI Reference Design
SLUC381C.ZIP (2519 KB)
SLUC408B.ZIP (205 KB)

Reference designs

Universal AC Input 10.6W/5V Adapter for Charger Applications, Compliant with EC CoC V5 (Tier2) Norms
PMP4450 This 5V2A charger solution is fully tested and passes EMI and EMC (CE) requirements. It implements a high efficiency primary side controller UCC28703. This design meet COC V5 Tier2 specification and measures 47mmX34mmX15mm and has been thermally characterized. A low cost EE16C general transformer is (...)
document-generic Schematic document-generic User guide

CAD/CAE symbols

Package Pins Download
SOT-23 (DBV) 6 View options

Ordering & quality

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UCC28740 Quick Charge Demo

Efficiency and performance of the UCC28740 constant voltage, constant current flyback controller.

Posted: 11-Mar-2014
Duration: 04:37

Get more information and order samples for UCC28740

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