R
EM6151
Enable - EN Output
The system enable output, EN , is inactive always when
RES is active and remains inactive after a RES pulse until
the watchdog is serviced correctly 3 consecutive times (i.e.
the TCL pulse must come in the open window). After three
consecutive services of the watchdog with TCL during the
open window, the EN goes active low.
could be energized each time reset goes inactive (time
allowed for the system to restart) and in this way the
electrical motors driven by the system could function out of
control. The circuit prevents the above failure mode by using
the EN output to disable the motor controls until software
has successfully cleared the watchdog three times (i.e. the
system has correctly re-started after a reset condition).
A malfunctioning system would be repeatedly reset by the
watchdog. In a conventional system critical motor controls
Typical Application
Regulated Voltage (5V)
VDD
Address decoder
EM6151
R1
VIN
TCL
RES
ROSC
Microprocessor
RES
100kΩ
VSS
EN
Motor
controls
EN
R2
GND
Fig. 8
Copyright © 2005, EM Microelectronic-Marin SA
rev. B / 06.06
7
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EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
