MAX697MJE/883B Maxim Integrated Products, MAX697MJE/883B Datasheet - Page 8

• Manufacturer Part Number: MAX697MJE/883B
• Description: Supervisory Circuits MPU Supervisor
• Manufacturer: Maxim Integrated Products

Specifications of MAX697MJE/883B

• Number Of Voltages Monitored: 1
• Monitored Voltage: 3 V to 5.5 V
• Output Type: Active High, Active Low, Push-Pull
• Manual Reset: Not Resettable
• Watchdog: Watchdog
• Battery Backup Switching: No Backup
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 3 V
• Supply Current (typ): 300 uA
• Maximum Power Dissipation: 600 mW
• Maximum Operating Temperature: + 125 C
• Mounting Style: Through Hole
• Package / Case: CDIP-16
• Minimum Operating Temperature: - 55 C
• Power Fail Detection: Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The MAX697 is nearly identical to the MAX696. The
MAX697 lacks the battery-backup feature, so it does
not have the V
allows the MAX697 to consume less than 250 microam-
peres, and it allows the inclusion of RAM write-protec-
tion pins. See Figure 2.
The battery-switchover circuit compares V
V
Switchover occurs when V
V
V
parator has 20mV of hysteresis to prevent repeated,
rapid switching if V
ly equal to the battery voltage.
When V
to V
50mA output current capability. Use an external pnp pass
transistor in parallel with the internal transistor if the out-
Microprocessor Supervisory Circuits
Figure 3. MAX696 Battery-Switchover Block Diagram
8
BATT
BATT
BATT
_______________________________________________________________________________________
Battery Switchover and V
OUT
BATTERY
INPUT
3V
input, and connects V
as V
as V
CC
V
+5V
CC
with a low-saturation pnp transistor. V
is higher than V
CC
CC
rises (see Figure 3). The switchover com-
falls, and when V
BATT
CC
V
BATT
, V
Detailed Description
falls very slowly or remains near-
700mV
V CC
OUT
BATT
OUT
, or BATT ON pins. This
CC
100mV
, V
CC
is 50mV greater than
CC
to whichever is higher.
BASE DRIVE
is internally switched
is 70mV more than
+
-
OUT
+
-
(MAX696)
MAX697
LOW IQ MODE SELECT
CC
OUT
to the
has
put current requirement at V
lower V
BATT ON output can directly drive the base of the
external transistor.
It should be noted that the MAX696 need only supply the
average current drawn by the CMOS RAM if there is ade-
quate filtering. Many RAM data sheets specify a 75mA
maximum supply current, but this peak current spike
lasts only 100ns. A 0.1µF bypass capacitor at V
plies the high instantaneous current, while V
only supply the average load current, which is much
less. A capacitance of 0.1µF or greater must be connect-
ed to the V
A 200Ω MOSFET connects the V
during battery backup. This MOSFET has very low
input-to-output differential (dropout voltage) at the low
current levels required for battery backup of CMOS
RAM or other low-power CMOS circuitry. When V
equals V
When V
ical supply current is only 600nA (typ), 1µA (max).
V
P
BATT
SIGNAL WHEN
SHUTDOWN
INTERNAL
> V
CC
p-CHANNEL
MOSFET
CC
+ 0.7V
CC
BATT
OUT
is between 0V and (V
- V
, the supply current is typically 12µA.
OUT
terminal to ensure stability.
V
OUT
voltage differential is desired. The
OUT
BATT
exceeds 50mA or if a
BATT ON
BATT
- 700mV), the typ-
0.1µF
input to V
REAL-TIME
OUT
TO CMOS
RAM AND
CLOCK
V
OUT
CC
IN
need
sup-
OUT
CC