UCC28740

ACTIVE

Constant-voltage, constant-current Flyback controller Using Opto-Coupler Feedback

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Product details

Parameters

Control method Secondary-side regulation Duty cycle (Max) (%) 99 Frequency (Max) (kHz) 100 UVLO thresholds on/off (V) 21/7.75 Features SSR, HV Start-up, DCM 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

  • Less than 10-mW No-Load Power Capability
  • Optocoupled Feedback for CV, and
    Primary-Side Regulation (PSR) for CC
  • Enables ±1% Voltage Regulation and ±5% Current Regulation Across Line and Load
  • 700-V Startup Switch
  • 100-kHz Maximum Switching Frequency Enables High-Power-Density Charger Designs
  • Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
  • Frequency Dithering to Ease EMI Compliance
  • Clamped Gate-Drive Output for MOSFET
  • Overvoltage, Low-Line, and Overcurrent Protection Functions
  • SOIC-7 Package
  • Create a Custom Design Using the UCC28740 With the WEBENCH® Power Designer

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Description

The UCC28740 isolated-flyback power-supply controller provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. Constant-Current (CC) regulation is accomplished through Primary-Side Regulation (PSR) techniques. This device processes information from opto-coupled feedback and an auxiliary flyback winding for precise high-performance control of output voltage and current.

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

Control algorithms in the UCC28740 allow operating efficiencies to meet or exceed applicable standards. 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 100 kHz and always maintains control of the peak-primary current in the transformer. Protection features keep primary and secondary component stresses in check. A minimum switching frequency of 170 Hz facilitates the achievement of less than 10-mW no-load power.

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Technical documentation

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Type Title Date
* Datasheet UCC28740 Constant-Voltage Constant-Current Flyback Controller Using Optocoupled Feedback datasheet (Rev. D) Mar. 23, 2018
Application notes Practical Feedback Loop Design Considerations for Flyback Converter Using May 20, 2020
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
Technical articles How to minimize time to market in your USB Type-C™ and USB Power Delivery designs Mar. 26, 2018
Technical articles Brush up on the latest motor design considerations for appliances Oct. 26, 2017
Technical articles Powering the IoT Jan. 26, 2017
Application notes Agency requirements for stand-by power consumption w/ offline and PoL converters Jan. 26, 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
User guides Using the UCC28740EVM-525 Jul. 02, 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
UCC24630 65W AC/DC Adapter
UCC24630EVM-636
document-generic User guide
99
Description

This is a high efficiency 65W AC/DC design using UCC24630 Synchronous Rectification Controller for a Universal input (85Vac to 265Vac) to 19.5V @3.33A output exceeding CoC-5 Tier2 and DOE Level VI performance requirements for external power supplies.

Features
  • 91.49% @115V AC, 89.81% @230V AC 4-point average efficiency 
  • 83.14% @120V AC, 82.24% @230V AC 10% load efficiency
  • 59mW No load Power consumption at 230V AC
  • Fast turn-on time
  • <80mV output voltage ripple
  • AC line input UVLO protection
EVALUATION BOARDS Download
document-generic User guide
49
Description

The UCC28740EVM-525 evaluation module is a 10W off-line discontinuous mode (DCM) flyback converter that provides constant-voltage (CV) and constant-current (CC) output regulation. It uses optical coupler feedback for tight voltage regulation and improved the transient response to large load steps (...)

Features
  • Universal AC input, 5V/2.1A output
  • <20mW no load power
  • Avg. efficiency > 80%
  • Opto-Coupled Feedback for Constant Voltage Regulation and Fast Dynamic Response
  • Primary Side Control for Tight Constant Current Performance (± 5% Output Current Regulation)
  • Internal 700V Start-Up Switch to Start up the Supply (...)

Design tools & simulation

SIMULATION MODELS Download
SLUM672A.ZIP (122 KB) - SIMPLIS Model
SIMULATION TOOLS Download
PSpice® for TI design and simulation tool
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 (...)
Features
  • 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
  • (...)
CALCULATION TOOLS Download
SLUC487B.ZIP (317 KB)

Reference designs

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CAD/CAE symbols

Package Pins Download
SOIC (D) 7 View options

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