Features
1.1 Features
UCC38500 PFC/PWM Combination Controller 100W Power Factor Correc- tion Preregulator include:
JCombines PFC and 2nd Stage Down Converter Controls
JControls Boost Preregulator to Near-unity Power Factor
JAccurate Power Limiting
JImproved Feedforward Line Regulation
JPeak Current Mode Control in Second Stage
JProgrammable Oscillator
JLeading Edge/Trailing Edge Modulation for Reduced Output Ripple
JLow Startup Supply Current
JSynchronized Second Stage with Programmable Soft-start
JProgrammable Second Stage Shut-down
1.2 Description
The UCC38500 provides all the functions necessary for active power factor correction and a second stage dc-to-dc converter all in one integrated circuit. The control IC uses leading edge modulation for the boost stage and trailing edge modulation for the step down converter to reduce the RMS current in the boost capacitor. The dc-to-dc controller uses peak current mode control for easy loop compensation.
The UCC38500 evaluation board is designed to illustrate the performance of the IC in a complete off-line 100W two-stage power converter using power fac- tor correction. The demonstration board was designed to operate with a uni- versal input voltage range (i.e. 85−265 Vac) with a regulated 12V dc output.
Caution
High-voltage levels are present on the evaluation module whenever it is energized. Proper precautions must be taken when working with the EVM. The output capacitor has high levels of energy storage and it must be discharged before the load is removed. Serious injury can occur if proper safety precautions are not followed.