Data Sheet

10

Rev. 1.9, 2007-07-30

TLE 6365

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 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

External loop compensation is required for converter stability, and is formed by

connecting a compensation resistor-capacitor series-network (

R

BUC and GND.

In the case of overload or short-circuit at

V

overcurrent threshold

I

the DMOS output transistor is switched off by the

overcurrent comparator immediately.

In order to protect the

V

an overvoltage protection is provided which switches off the output transistor as soon as

the voltage at pin

V

6.0 V.

Also a battery undervoltage protection is implemented in the TLE 6365 to avoid wrong

operation of the following supplied devices, the typical threshold when decreasing the

battery voltage is at