Data Sheet Rev. 1.2

19

2003-06-02

TLE 6363

Buck Converter

A stabilized logic supply voltage (typ. 5 V) for general purpose is realized in the system

by a buck converter. An external buck-inductance

L

DMOS power transistor with the programmed frequency (pin R).

The buck regulator supply is given by the boost converter output

V

battery power-down the stored energy of the boost converter capacitor is used.

Like the boost converter, the buck converter uses the temperature compensated

bandgap reference voltage (typ. 2.8 V) for its regulation loop.

This reference voltage is connected to the non-inverting input of the error amplifier and

an internal voltage divider supplies the inverting input. Therefore the output voltage

V

CC

is fixed due to the internal resistor ratio to typ. 5.0 V.

The output of the error amplifier goes to the inverting input of the PWM comparator as

well as to the buck compensation output BUC.

When the error amplifier output voltage exceeds the sawtooth voltage the output power

MOS-transistor is switched on. So the duration of the output transistor conduction phase

depends on the

V