Texas Instruments UCC38500EVM - Manual (Page 8)

Features
1-2
1.1 Features
UCC38500 PFC/PWM Combination Controller 100W Power Factor Correc-
tion Preregulator include:
J Combines PFC and 2nd Stage Down Converter Controls
J Controls Boost Preregulator to Near-unity Power Factor
J Accurate Power Limiting
J Improved Feedforward Line Regulation
J Peak Current Mode Control in Second Stage
J Programmable Oscillator
J Leading Edge/Trailing Edge Modulation for Reduced Output Ripple
J Low Startup Supply Current
J Synchronized Second Stage with Programmable Soft-start
J Programmable 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.