MAX795RCSA+T Maxim Integrated Products, MAX795RCSA+T Datasheet - Page 17

• Manufacturer Part Number: MAX795RCSA+T
• Description: IC SUPERVISOR MPU 8-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Battery Backup Circuitr

Specifications of MAX795RCSA+T

• Number Of Voltages Monitored: 1
• Output: Open Drain or Open Collector
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 2.625V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Monitored Voltage: 3 V, 3.3 V
• Output Type: Active Low, Open Drain
• Manual Reset: Not Resettable
• Watchdog: No Watchdog
• Battery Backup Switching: Backup
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1 V
• Supply Current (typ): 49 uA
• Maximum Power Dissipation: 471 mW
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Power Fail Detection: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 16. Adding Hysteresis to the Power-Fail Comparator: (a) Symmetrical Hysteresis, (b) Hysteresis Only on Rising V
These µP supervisors can monitor either positive or
negative supplies using a resistor voltage divider to
PFI. PFO can be used to generate an interrupt to the µP
or to cause reset to assert (Figure 12).
Since the RESET output is open drain, the MAX793/
MAX794/MAX795 interface easily with µPs that have
bidirectional reset pins, such as the Motorola 68HC11.
Connecting the RESET output of the µP supervisor
directly to the RESET input of the microcontroller with a
single pullup resistor allows either device to assert
reset (Figure 17).
These supervisors are relatively immune to short-dura-
tion negative-going V
ing resets to the µP during power-up, power-down, and
brownout conditions. Therefore, resetting the µP when
V
ommended.
CC
(a)
experiences only small glitches is usually not rec-
Monitoring an Additional Power Supply
PFO
R1
R2
V
V
0V
V
TRIP
H
L
V
= (V
= R1 V
0V
IN
= V
Negative-Going V
PFT
PFT
PFT
+ V
______________________________________________________________________________________
(
R1 + R2
PFH
C1*
(
CC
R2
1
R1
) (R1)
TO µP
+
Bidirectional Reset Pins
)
transients (glitches) while issu-
1
R2
R3
(
Interfacing to µPs with
3.0V/3.3V Adjustable Microprocessor
1
R1
+
V
L
+
1
R3
PFI
PFO
1
R2
)
V
TRIP
+
–
V
R3
1
CC
R3
MAX793
MAX794
)
GND
V
WHERE
CC
V
CC
H
Transients
V
V
PFT
PFH
*OPTIONAL
= 1.237V
= 10mV
V
IN
(b)
Figure 17. Interfacing to µPs with Bidirectional Reset I/O
V
CC
GENERATOR
Supervisory Circuits
RESET
PFO
V
V
MAX793
MAX794
MAX795
TRIP
WHERE
H
R1
R2
V
GND
0V
CC
= R1 (V
V
= V
0V
IN
PFT
V
V
PFT
PFH
PFT
V
V
(
R1 + R2
D
L
RESET
+ V
= 1.237V
= DIODE FORWARD VOLTAGE DROP
= V
= 10mV
N
R2
C1*
TRIP
PFH
TO µP
)
)
(
R1
R3
1
V
+
TRIP
R2
PFI
PFO
1
+
1
R3
RESET
MAX793
MAX794
)
GND
V
–
CC
V
H
V
R3
D
V
µP
GND
CC
*OPTIONAL
IN
V
IN
17