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UCC28740

ACTIVE

Constant-Voltage, Constant-Current (CVCC) Flyback controller with Secondary Side Regulation (SSR)

Product details

Control mode Secondary-side regulation UVLO thresholds on/off (V) 21/7.75 Switching frequency (max) (kHz) 100 Features Current limiting, DCM, High voltage startup, High-voltage startup, Light load efficiency, Light-load efficiency, Overcurrent protection, Overvoltage protection, SSR, Secondary-side regulated, Soft start, Valley switching Operating temperature range (°C) -40 to 125 Rating Catalog Topology Flyback
Control mode Secondary-side regulation UVLO thresholds on/off (V) 21/7.75 Switching frequency (max) (kHz) 100 Features Current limiting, DCM, High voltage startup, High-voltage startup, Light load efficiency, Light-load efficiency, Overcurrent protection, Overvoltage protection, SSR, Secondary-side regulated, Soft start, Valley switching Operating temperature range (°C) -40 to 125 Rating Catalog Topology Flyback
SOIC (D) 7 29.4 mm² 4.9 x 6
  • 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
  • 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

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.

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
* Data sheet UCC28740 Constant-Voltage Constant-Current Flyback Controller Using Optocoupled Feedback datasheet (Rev. D) PDF | HTML 23 Mar 2018
Technical article How to design a limited power source industrial AC/DC power supply with minimal components – part 1 PDF | HTML 11 Jan 2024
Application brief Flyback Selection Guide PDF | HTML 23 Jun 2022
Product overview CCS-Compliant EV Service Equipment Reference Design for Level 1 and 2 EV Charger 16 Jun 2022
Application note Flyback Aux Winding OVP and UVLO Fault Sensing Design and Troubleshooting Tips PDF | HTML 31 Aug 2021
Application note Practical Feedback Loop Design Considerations for Flyback Converter Using PDF | HTML 20 May 2020
Application note Minimize Standby Consumption for UCC287XX Family 01 Aug 2019
Technical article Choosing the right flyback controller for your design PDF | HTML 24 Aug 2018
Application note Selecting Electrolitic Bus Capacitor for Universal Input 17 Jul 2018
Technical article How to minimize time to market in your USB Type-C™ and USB Power Delivery designs PDF | HTML 26 Mar 2018
Technical article Brush up on the latest motor design considerations for appliances PDF | HTML 26 Oct 2017
Technical article Powering the IoT PDF | HTML 26 Jan 2017
Technical article How to design a limited power source industrial AC/DC power supply - part 2 PDF | HTML 26 Oct 2016
Analog Design Journal Agency requirements for stand-by power consumption w/ offline and PoL converters 26 Jan 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
EVM User's guide Using the UCC28740EVM-525 02 Jul 2013

Design & development

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

Evaluation board

UCC24630EVM-636 — UCC24630 65W AC/DC Adapter

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.

User guide: PDF
Not available on TI.com
Evaluation board

UCC28740EVM-525 — UCC28740EVM-525 Evaluation Module

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 (...)

User guide: PDF
Not available on TI.com
Simulation model

UCC28740 SIMPLIS Transient Model (Rev. A)

SLUM672A.ZIP (122 KB) - SIMPLIS Model
Calculation tool

SLUC487 UCC28740 Design Calculator

Supported products & hardware

Supported products & hardware

Products
Flyback controllers
UCC28740 Constant-Voltage, Constant-Current (CVCC) Flyback controller with Secondary Side Regulation (SSR) UCC28740-Q1 Automotive ultra low standby, flyback controller with integrated HV startup and optocoupler feedback

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SOIC (D) 7 View options

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