UCC28742 High-Efficiency Flyback Controller With Optocoupler Feedback | TI.com

UCC28742 (ACTIVE) High-Efficiency Flyback Controller With Optocoupler Feedback

 

Description

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.

Features

  • 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

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WEBENCH ® Designer UCC28742

 AC  DC  
AC Frequency  60 Hz  50 Hz
Use Isolated Output?
Rectification Type
  Min   Max Range
VinRMS -  V
Vout  V
Iout  A
Ambient Temp  °C

Parametrics

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Part number Order Control method Duty cycle (Max) (%) Frequency (Max) (kHz) UVLO thresholds on/off (V) Features Operating temperature range (C) Package Group Rating Package size: mm2:W x L (PKG)
UCC28742 Order now Secondary-side regulation     99     105     22/7.7     SSR
DCM    
-40 to 125     SOT-23 | 6     Catalog     6SOT-23: 5 mm2: 1.6 x 2.9 (SOT-23 | 6)    
UCC28700 Order now Primary-side regulation     99     132     21/8.1     PSR
DCM    
-20 to 125     SOT-23 | 6     Catalog     6SOT-23: 5 mm2: 1.6 x 2.9 (SOT-23 | 6)    
UCC28704 Order now Primary-side regulation     99     85     21/7.7     PSR
DCM    
-40 to 125     SOT-23 | 6     Catalog     6SOT-23: 5 mm2: 1.6 x 2.9 (SOT-23 | 6)    
UCC28710 Order now Primary-side regulation     99     100     21/8     PSR
DCM
HV Start-up
Green Mode
Input Line Monitor
Leading Edge Blanking
Light Load Efficiency
Low Power
Soft Start    
-40 to 125     SOIC | 7     Catalog     7SOIC: 29 mm2: 6 x 4.9 (SOIC | 7)    
UCC28720 Order now Primary-side regulation     99     80     21/7.7     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    
-40 to 125     SOIC | 7     Catalog     7SOIC: 29 mm2: 6 x 4.9 (SOIC | 7)    
UCC28722 Order now Primary-side regulation     99     80     21/7.7     PSR
DCM    
-40 to 125     SOT-23 | 6     Catalog     6SOT-23: 5 mm2: 1.6 x 2.9 (SOT-23 | 6)    
UCC28740 Order now Secondary-side regulation     99     100     21/7.75     SSR
HV Start-up
DCM    
-40 to 125     SOIC | 7     Catalog     7SOIC: 29 mm2: 6 x 4.9 (SOIC | 7)