3

4761B–AUTO–09/05

T6801

4.

Functional Description

4.1

General

ON state: Low level at the input stage activates the output stage.

OFF state: The internal pull-up resistor provides high level to the input comparator and deacti-

vates the output stage.

A 7V Zener diode between input pin and GND is capable of ±10 mA clamping current.

4.2

Current Limitation of the Output Stages and Overtemperature Shutdown

A temperature-dependent current limitation in the range of 25 to 100 mA protects the stage in

case of a short circuit. Additionally, the chip temperature is monitored. For T

output is disabled and automatically enabled with a hysteresis of T

4.3

Transients and Load Dump

An integrated 28V Zener diode protects the output stage against transients and load-dump

(Schaffner pulses). With the help of an external 1 k

Ω resistor, the output transistor is capable of

handling the corresponding current which flows during each of these conditions. Apart from that,

the output is short-circuit and overload protected.

4.4

Low-voltage Detection

When the supply voltage is switched on, a power-on reset pulse is generated internally which

disables the output stage until a defined supply-voltage level is reached. The low-voltage detec-

tion is provided with a hysteresis of V

Figure 4-1.

Application Schematic

V

V

I

V

O

C

R

V

Batt

1 k

Ω

470 pF

Load

100 nF

Micro-

controller

T6801