AN667 Datasheet (ST Micro) - DESIGNING A HIGH POWER FACTOR SWITCHING PREREGULATOR

AN667, DESIGNING A HIGH POWER FACTOR SWITCHING PREREGULATOR

Supply Block (see fig.

2): A precise bandgap reference is internally built to ensure a good regulation.

The undervoltage comparator with hysteresis and the very-low supply current, before the turn-on threshold is reached, allows to minimize the startup and supply circuitry.

Figure 2: Supply Block Di

® APPLICATION NOTE DESIGNING A HIGH POWER FACTOR SWITCHING PREREGULATOR WITH THE L6560/A TRANSITION MODE I.C.

by G.

Comandatore and U.

Moriconi Active power factor correction techniques are going to grow in conversion applications.

Market interest (legislation to be considered) is also moving towards fairly low (36-150W) conversion power ranges (lighting, monitor).

This paper describes an "easy to use" 8 Pin Controller that allows the realization of very low cost offline Power Factor Correcti

AN667 Features

* are:

* Undervoltage lockout with hysteresis and micropower start-up.

* Stable error amplifier.

* Output overvoltage protection.

* Transition Mode Operating

* Zero Current and coil Voltage detection.

* Internal start oscillator. Device Blocks Descriptio