Datasheet

Interfacing to μPs with
Bidirectional Reset Pins
μPs with bidirectional reset pins, such as the Motorola
68HC11 series, can contend with the MAX705–MAX708
RESET output. If, for example, the RESET output is
driven high and the μP wants to pull it low, indeterminate
logic levels may result. To correct this, connect a 4.7kΩ
resistor between the RESET output and the μP reset I/O,
as in Figure 8. Bu󰀨er the RESET output to other system
components.
Figure 5. RESET Valid to Ground Circuit
Figure 7. Monitoring a Negative Voltage
Figure 6. Monitoring Both +5V and +12V
Figure 6. Monitoring Both +5V and +12V
MAX70_
RESET
R1
MAX70_
RESET
R2
R1
+5V
V-
V
CC
PFI
GND
MR
PFO
TO µP
100kΩ
100kΩ
2N3904
MR
PFO
+5V
0V
+5V
0V
V
TRIP 0V
V-
5 1.25
R1
1.25 V
TRIP
R2
,V
TRIP
0
–
=
–
<
MAX70_
RESET
130kΩ
1%
PARAMETER
MIN TYP
MAX UNIT
+12V Reset
Threshold at +25°C
10.67
10.87
11.50 V
1MΩ
1%
+5V
+12V
V
CC
PFI
GND
MR
PFO
TO µP
MAX70_
BUFFERED RESET TO OTHER SYSTEM COMPONENTS
4.7kΩ
V
CC
GND
RESET
V
CC
GND
RESET
µP
MAX705–MAX708/MAX813L MAX705–MAX708/MAX813L
Low-Cost, μP Supervisory Circuits
www.maximintegrated.com
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