+3V Voltage Monitoring, Low-Cost µP
Supervisory Circuits
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T
sees 1.25V when V
IN
falls to the desired trip point
(V
TRIP
). Resistor R3 adds hysteresis. R3 will typically
be an order of magnitude greater than R1 and R2. The
current through R1 and R2 should be at least 1µA to
ensure that the 25nA (max) PFI input current does not
shift the trip point significantly. R3 should be larger than
10kΩ to prevent it from loading down the
PFO
pin.
Capacitor C1 adds noise rejection.
Monitoring a Negative Voltage
The power-fail comparator can be used to monitor a
negative supply voltage using the circuit of Figure 8.
When the negative supply is valid,
PFO
is low. When
the negative supply voltage drops,
PFO
goes high. This
circuit’s accuracy is affected by the PFI threshold toler-
ance, the V
CC
voltage, and resistors R1 and R2.
Bypassing V
CC
For noisy systems, bypass V
CC
with a 0.1µF capacitor
to GND.
Ordering Information (continued)
PART†
MAX706PEUA
MAX706PMJA
MAX706RCPA
MAX706RCSA
MAX706RCUA
MAX706REPA
MAX706RESA
MAX706REUA
MAX706RMJA
MAX706SCPA
MAX706SCSA
MAX706SCUA
MAX706SEPA
MAX706SESA
MAX706SEUA
MAX706SMJA
MAX706TCPA
MAX706TCSA
MAX706TCUA
MAX706TEPA
MAX706TESA
MAX706TEUA
MAX706TMJA
MAX706APE
PA
MAX706APESA
MAX706APEUA
MAX706AREPA
MAX706ARESA
MAX706AREUA
MAX706ASEPA
TEMP
RANGE
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8µMAX
8 Plastic Dip
PKG
CODE
U8-1
J8-2
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
J8-2
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
J8-2
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
J8-2
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
P8-1
PART†
MAX706ASESA
MAX706ASEUA
MAX706ATEPA
MAX706ATESA
MAX706ATEUA
MAX708RCPA
MAX708RCSA
MAX708RCUA
MAX708REPA
MAX708RESA
MAX708REUA
MAX708RMJA
MAX708SCPA
MAX708SCSA
MAX708SCUA
MAX708SEPA
MAX708SESA
MAX708SEUA
MAX708SMJA
MAX708TCPA
MAX708TCSA
MAX708TCUA
MAX708TEPA
MAX708TESA
MAX708TEUA
MAX708TMJA
TEMP
RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-
PACKAGE
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 CERDIP*
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 CERDIP*
8 Plastic Dip
8 SO
8 µMAX
8 Plastic Dip
8 SO
8 µMAX
8 CERDIP*
PKG
CODE
S8-2
U8-1
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
J8-2
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
J8-2
P8-1
S8-2
U8-1
P8-1
S8-2
U8-1
J8-2
-55°C to +125°C 8 CERDIP*
-55°C to +125°C 8 CERDIP*
-55°C to +125°C 8 CERDIP*
-55°C to +125°C 8 CERDIP*
†
SO, µMAX, and PDIP packages are available in lead-free.
*Contact factory for availability and processing to MIL-STD-883.
**Future product—contact factory for availability.
Chip Information
PROCESS: CMOS
10
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