Interfacing to µPs with
Bidirectional Reset Pins
µPs with bidirectional reset pins (such as the Motorola
68HC11 series) can contend with the AMS811/AMS812
reset outputs. If, for example, the AMS811 RESET out-
put is asserted high and the µP wants to pull it low,
indeterminate logic levels may result. To correct such
cases, connect a 4.7kΩ resistor between the AMS811
RESET (or AMS812 RESET) output and the µP reset I/O
(Figure 3). Buffer the reset output to other system com-
ponents.
BUFFERED RESET
TO OTHER SYSTEM
COMPONENTS
BUFFER
V
CC
V
CC
μP
AMS811
4.7k
RESET
RESET
GND
GND
Figure 3. Interfacing to µPs with Bidirectional Reset I/O
Advanced Monolithic Systems http://www.ams-semitech.com
AMS [ Advanced Monolithic Systems Ltd ]
