Product details

Control mode Secondary-side regulation Frequency (Max) (kHz) 105 UVLO thresholds on/off (V) 22/7.7 Duty cycle (Max) (%) 99 Features SSR, DCM, Soft Start, Current Limiting, OVP, Light Load Efficiency Operating temperature range (C) -40 to 125 Rating Catalog Device type Controllers Topology Flyback
Control mode Secondary-side regulation Frequency (Max) (kHz) 105 UVLO thresholds on/off (V) 22/7.7 Duty cycle (Max) (%) 99 Features SSR, DCM, Soft Start, Current Limiting, OVP, Light Load Efficiency Operating temperature range (C) -40 to 125 Rating Catalog Device type Controllers Topology Flyback
SOT-23 (DBV) 6 5 mm² 2.9 x 1.6
  • Opto-Coupled Feedback Enables up to 1% Regulation
  • Accurate Current Limit with Overload Timeout Protection and Delayed Hiccup Response
  • Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
  • 80-kHz Maximum Switching Frequency
  • Frequency Dithering to Ease EMI Compliance
  • Clamped Gate-Drive Output for MOSFET
  • Ultra-Low Start-Up Current and Large VDD Hysteresis
    • High Value Start-Up Resistor
    • Low Bias Capacitance
  • Fault Protections
    • Input Low Line
    • Output Over-Voltage
    • Over-Current
    • Short-Circuit
  • SOT23-6 Package
  • Create a Custom Design Using the UCC28742 with the WEBENCH® Power Designer
  • Opto-Coupled Feedback Enables up to 1% Regulation
  • Accurate Current Limit with Overload Timeout Protection and Delayed Hiccup Response
  • Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
  • 80-kHz Maximum Switching Frequency
  • Frequency Dithering to Ease EMI Compliance
  • Clamped Gate-Drive Output for MOSFET
  • Ultra-Low Start-Up Current and Large VDD Hysteresis
    • High Value Start-Up Resistor
    • Low Bias Capacitance
  • Fault Protections
    • Input Low Line
    • Output Over-Voltage
    • Over-Current
    • Short-Circuit
  • SOT23-6 Package
  • Create a Custom Design Using the UCC28742 with the WEBENCH® Power Designer

The UCC28742 off-line flyback controller is a highly integrated, 6-pin secondary-side regulated PWM controller for efficient AC-to-DC power supplies. It is an isolated-flyback power-supply controller that provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. This device processes information from opto-coupled feedback and an auxiliary flyback winding for high-performance control of output voltage and current.

The UCC28742 employs advanced control algorithms to achieve high operating efficiency and performance. 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 80 kHz and always maintains control of the peak-primary current in the transformer. A minimum switching frequency of 200 Hz facilitates the achievement of low no-load input power.

The UCC28742 off-line flyback controller is a highly integrated, 6-pin secondary-side regulated PWM controller for efficient AC-to-DC power supplies. It is an isolated-flyback power-supply controller that provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. This device processes information from opto-coupled feedback and an auxiliary flyback winding for high-performance control of output voltage and current.

The UCC28742 employs advanced control algorithms to achieve high operating efficiency and performance. 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 80 kHz and always maintains control of the peak-primary current in the transformer. A minimum switching frequency of 200 Hz facilitates the achievement of low no-load input power.

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Technical documentation

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Type Title Date
* Data sheet UCC28742 High-Efficiency Flyback Controller with Optocoupler Feedback datasheet (Rev. A) 08 May 2018
Application note Flyback Aux Winding OVP and UVLO Fault Sensing Design and Troubleshooting Tips 31 Aug 2021
More literature PCB layout guidelines to optimize power supply performance 23 Mar 2021
Application note Minimize Standby Consumption for UCC287XX Family 01 Aug 2019
Technical article Choosing the right flyback controller for your design 24 Aug 2018
Application note Selecting Electrolitic Bus Capacitor for Universal Input 17 Jul 2018
User guide Using the UCC28742EVM-001 (Rev. B) 06 Jun 2018

Design & development

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

Simulation model

UCC28742 SIMPLIS Model (Rev. A)

SLUJ001A.ZIP (840 KB) - SIMPLIS Model
Calculation tool

UCC28742 Design Calculator (Rev. B)

SLUC652B.ZIP (301 KB)
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SOT-23 (DBV) 6 View options

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