U5020M

Preliminary Information

TELEFUNKEN Semiconductors

Rev. A3, 27-Feb-97

1 (8)

Digital Window Watchdog Timer

Description

The digital window watchdog timer, U5020M, is a CMOS

integrated circuit. In application where safety is critical,

it is especially important to monitor the microcontroller.

Normal microcontroller operation is indicated by a cycli-

cally transmitted trigger signal, which is received by a

window watchdog timer within a defined time window. A

missing or a wrong trigger signal makes the watchdog

timer reset the microcontroller. The IC is tailored for

microcontrollers which can work in both full-power and

sleep mode. With an additional voltage monitoring

(power-on reset and supply voltage drop reset) U5020M

offers a complete monitoring solution for microsystems

in automotive and industrial applications.

Features

D RC–oscillator

D Internal reset during power-up and supply voltage

drops (POR)

D “Short” trigger window for active mode

“long” trigger window for sleep mode

D Cyclical wake-up of microcontroller in sleep mode

D Trigger input

D Six wake-up inputs

D Reset output

D Enable output

Ordering Information

Extended Type Number

Package

Remarks

U5020M–FP

SO16

Block Diagram

Input signal

conditioning

OSC

POR

12

11

Power–on

reset

16

10

Mode

Trigger

RC

Oscillator

State machine

POR

OSC

Reset

mC

Test logic

3–8

2

1

Test

Test

Wake up

External

switching

circuitry

9

14

Enable

GND

15

13

C

10 nF

OSC

95 10387

Figure 1. Block diagram with external circuit