Texas Instruments UCC28740 | Demoboard UCC28740EVM-525

Description

This evaluation module uses the UCC28740 Constant-Voltage, Constant-Current Flyback ControllerUsing Opto-Coupled Feed-Back in a 10 W converter to provide 2 A of constant charge current. Theinput accepts a voltge range of 85 VAC to 265 VAC. The output is designed for 5 V when inconstant voltage mode and will deliver 2.1 A of constant charge down to an output voltage of lessthan 2 V. Depending upon the operating conditions, the control law algorithm will modulate theswitching frequency or the peak primary current to satisfy the power transfer requirements. As theload is increased from zero, the converter will transition through a frequency modulation modewhere the peak primary current is held constant at one-quarter of its full-load peak value as theswitching frequency increases from a minimum value to maintain energy transfer up to 32 kHz.When the load is increased to the level at which the switching frequency reaches 32 kHz, thecontroller will keep the switching frequency fixed and modulate the peak primary current, increasingit from one-quarter its peak value up to its maximum full load peak current value; this area ofoperation is refered to as the amplitude modulation range. Further increase in load demand willtransition the controller into another frequency modulation mode where the peak primary current isconstant at its maximum designed value and the switching frequency is increased as needed, up tothe controller’s maximum 100 kHz switching frequency. Opto-coupled feed-back maintains a tightlyregulated output with fast dynamic response to load transients. The controller will further enhanceits efficient operation with valley switching. The UCC28740 also uses dithering of the gate drivehelps to ease EMI compliance.This user’s guide provides the schematic, component list, assembly drawing, art work, and test setup necessary to evaluate the UCC28740 in a typical off-line converter application.

Features

The UCC28740EVM-525 features include:

• AC Input Range 85 VAC to 265 VAC
• DC Output of 5 V, 2.1 A
• No-Load Power Consumption less than 20 mW
• Opto-Coupled Feedback for Constant Voltage Regulation and Fast Dynamic Response
• Primary Side Control for Tight Constant Current Performance
• ± 3% Output Volage Regulation
• ± 5% Output Current Regulation
• Average Efficiency > 80%
• Output Over Current and Short Circuit Protection
• Output Over Voltage Protection
• Input Brown-Out Protection
• Auto Re-Start on Fault
• Quasi-Resonant Valley Switching
• Frequency Dither
• Internal 700V Start-Up Switch to Start up the Supply Directly From the Bulk Rail

Typical applications

• USB-Compliant Adapters and Chargers for Consumer Electronics such as smart phones, tablet,Stand-by Supply for TV and Desktop
• White Goods

More information

• Datasheet
• IC product information