MAX690TMJA Maxim Integrated, MAX690TMJA Datasheet - Page 10

• Manufacturer Part Number: MAX690TMJA
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX690R, MAX690S, MAX690T, MAX704R, MAX704S, MAX704T, MAX802, MAX802R, MAX802S, MAX802T, MAX804, MAX804R, MAX804S, MAX804T, MAX805, MAX805R, MAX805S, MAX805T, MAX806, MAX806R, MAX806S, MAX806Tr

Specifications of MAX690TMJA

• Number Of Voltages Monitored: 1
• Monitored Voltage: 4.65 V
• Output Type: Active Low, Push-Pull
• Manual Reset: Not Resettable
• Watchdog: Watchdog
• Battery Backup Switching: Backup
• Supply Voltage - Max: 5.5 V
• Chip Enable Signals: No
• Power Fail Detection: Yes
• Supply Current (typ): 350 uA
• Supply Voltage - Min: 1 V

3.0V/3.3V Microprocessor Supervisory Circuits
Figure 4. a) Adding Additional Hysteresis to the Power-Fail Comparator
Figure 5. Using the Power-Fail Comparator to Monitor an Additional Power Supply
10
a
a
______________________________________________________________________________________
PFO
V
V
TRIP
CC
V
L
PFO
= R
= R
R
R
R
R
V
0V
V
2
2
V
1
2
1
2
TRIP
H
L
V
(V
= (V
(V
V-
= R
0V
IN
PFT
PFT
= V
1
PFT
PFT
+ V
)
V
(
PFT
+ V
PFH
1
R
(
1
R
PFH
C1*
1
+
)
(
R
+ R
(
1
R
) (R
2
1
R
TO μP
1
1
R
2
2
+
1
1
)
)
)
+
1
R
–
R
(
PFI
2
3
R
1
R
1
V
+
2
1
CC
R
V
V
L
1
+
L
)
1
R
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
PFI
PFO
–
3
1
R
)
2
V
V
CC
TRIP
R
–
V
+
V
GND
1
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
TRIP
CC
V
1
R
CC
R
3
3
3.0V OR 3.3V
)
GND
V
CC
V
WHERE
H
WHERE
NOTE: V
PFO
0V
V
V
PFT
PFH
TRIP
V
V
*OPTIONAL
PFT
PFH
= 1.237V
= 10mV
IS NEGATIVE
= 1.237V
= 10mV
V
IN
V-
b
b
b) Shifting the Additional Hysteresis above V
PFO
V
CC
V
V
TRIP
H
= (V
PFO
V
R
R
V
=
1
2
TRIP
WHERE
R
R
H
PFT
0V
1
2
V
V
= R
PFT
IN
V
= V
+ V
0V
IN
1
PFT
(
(V
V
V
PFH
R
PFT
PFH
PFT
1
V
V
R
D
(
L
+ R
)
R
2
(
+ V
1
= 1.237V
= DIODE FORWARD VOLTAGE DROP
= V
= 10mV
2
R
R
+ R
C1*
1
2
TRIP
)
PFH
R
+ R
2
2
TO μP
)
)
2
V
(
PFI
TRIP
)
R
1
R
3
1
V
+
TRIP
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
PFI
PFO
1
R
V
2
H
+
V
GND
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
CC
1
R
3
3.0V OR 3.3V
)
GND
V
–
CC
V
(V
H
* MAX704T/S/R,
CC -
MAX806T/S/R ONLY
PFO
MR
R
3
V
D
PFT
)
*OPTIONAL
*
V
V
IN
IN