MAX705 Maxim, MAX705 Datasheet - Page 8

• Manufacturer Part Number: MAX705
• Description: Low-Cost / uP Supervisory Circuits
• Manufacturer: Maxim

Low-Cost, µP Supervisory Circuits
Figure 5. RESET Valid to Ground Circuit
Figure 7. Monitoring a Negative Voltage
8
+5V
PFO
V-
_______________________________________________________________________________________
MR
R1
R2
+5V
+5V
0V
0V
5 1.25
R1
MAX70_
V-
1.25
RESET
PFI
R2
MAX70_
V TRIP
GND
V
CC
V
RESET
TRIP
PFO
, V TRIP
MR
R1
100k
0V
0
2N3904
TO P
100k
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. Buffer the RESET output to other system
components.
Figure 6. Monitoring Both +5V and +12V
Figure 8. Interfacing to µPs with Bidirectional Reset I/O
130k
1%
1M
1%
MAX70_
+12V Reset
Threshold at +25°C
GND
V
+12V
CC
PARAMETER
RESET
+5V
BUFFERED RESET TO OTHER SYSTEM COMPONENTS
4.7k
PFI
V
CC
10.67 10.87 11.50
Bidirectional Reset Pins
MIN
Interfacing to µPs with
MAX70_
GND
TYP
RESET
PFO
MR
RESET
MAX
GND
V
CC
UNIT
P
V
TO P