TLE 4260

Semiconductor Group

3

1998-11-01

Circuit Description

The control amplifier compares a reference voltage, which is kept highly accurate by

resistance adjustment, to a voltage that is proportional to the output voltage and drives

the base of the series transistor via a buffer. Saturation control as a function of the load

current prevents any over-saturation of the power element. If the output voltage goes

below 96% of its typical value, an external capacitor is discharged on pin 4 by the reset

generator. If the voltage on the capacitor reaches the lower threshold V

is issued on pin 2 and not cancelled again until the upper threshold V

an output current of less than I

generator. The latter is turned on again when the output current increases, the output

voltage drops below 4.2 V or the delay capacitor is discharged by external measures.

The IC also incorporates a number of internal circuits for protection against:

•Overload

• Overvoltage

• Overtemperature

• Reverse polarity

Block Diagram

Overvoltage

Monitoring

Saturation

Control and

Protection

RESET

Generator

Temperature

Sensor

Adjustment

BANDGAP

Reference

-

+

7

4

2

3

1

Input

GND

Output

RESET

Delay

RESET

AEB00578

Circuit

STANDBY

Changeover

Amplifier

Control

Buffer