TLE 4263

Semiconductor Group

4

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 externally scaled down

output voltage at the reset threshold input drops below 1.35 V, the external reset delay

capacitor is discharged by the reset generator. If the voltage on the capacitor reaches

the lower threshold

V

again until the upper threshold

V

to GND, reset is triggered at an output voltage of 4.5 V. A connected microcontroller is

controlled by the watchdog logic. If pulses are missing, the reset output is set to low. The

pulse sequence time can be set within a wide range with the reset delay capacitor. The

IC can be switched at the TTL-compatible, low-active inhibit input. The IC also

incorporates a number of internal circuits for protection against:

q

Overload

q

Overtemperature

q

Reverse polarity

Block Diagram

Input

18

AEB01100

20

GND

4-7, 14-17

Output

12

9

3

10

Reset

Delay

Reset

Output

Reset

Threshold

Watchdog

11

Temperature

Sensor

Generator

Reset

Reference

Bandgap

Adjustment

Buffer

Control

Amplifier

Saturation

Control and

Protection

Circuit

Inhibit