TLE 6711

Circuit Description

Data Sheet V 2.22

12

2001-04-23

2

Circuit Description

Below some important sections of the TLE 6711 are described in more detail.

2.1

Power On Reset

In order to avoid any system failure, a sequence of several conditions has to be passed.

In case of

V

pin RO to reset an external microcontroller. When the level of

V

threshold

V

beforeswitchingtoHIGH. If

V

the reset reaction time

t

period

t

“glitches” on the

V

Figure 3

Reset Function

2.2

Watchdog Operation

The watchdog uses one hundred of the oscillator’s clock signal period as a timebase,

defined as the watchdog cycle time

t

After power-on, the reset output signal at the RO pin (microcontroller reset) is kept LOW

for the reset delay time

t

at RO the device starts the closed window time

t

this window is interpreted as a pretrigger failure according to the figures shown below.

After the closed window the open window with the duration

t

AET02950

L

H

RO

Invalid

RT

V

typ. 4.65 V

t

t

Start-Up

ON Delay

Invalid

Invalid

ON Delay

Started

Stopped

RD

t

RR

t

RD

t

t

t

Power

Start-Up

Normal

Failed

N

Failed

Normal

1 V

ON Delay