MAX691ACWE+ Maxim Integrated Products, MAX691ACWE+ Datasheet - Page 12

• Manufacturer Part Number: MAX691ACWE+
• Description: IC MPU SUPERVISOR CIRCUIT 16SOIC
• Manufacturer: Maxim Integrated Products
• Type: Battery Backup Circuitr

Specifications of MAX691ACWE+

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Push-Pull
• Reset: Active High/Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 4.65V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Monitored Voltage: 0 V to 5.5 V
• Undervoltage Threshold: 4.5 V
• Overvoltage Threshold: 4.75 V
• Manual Reset: No
• Watchdog: Yes
• Battery Backup Switching: Yes
• Power-up Reset Delay (typ): 280 ms
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 0 V
• Supply Current (typ): 100 uA
• Maximum Power Dissipation: 762 mW
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 70 C
• Chip Enable Signals: Yes
• Minimum Operating Temperature: 0 C
• Output Type: Active High or Active Low or Open Drain
• Power Fail Detection: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The Battery-Backup Input (VBATT) is similar to the V
input except the PMOS switch and parallel diode are
much smaller. Accordingly, the on-resistances of the
diode and the switch are each approximately 10Ω.
Continuous current should be limited to 25mA and
peak currents (only during power-up) limited to 250mA.
The reverse leakage of this input is less than 1µA over
temperature and supply voltage (Figure 8).
The Output Supply Voltage (V
nected to the substrate of the IC and supplies current
to the external system and internal circuitry. All open-
circuit outputs will, for example, assume the V
age in their high states rather than the V
the maximum source current of 250mA, V
cally be 200mV below V
a 0.1µF capacitor.
The MAX691A/MAX693A/MAX800L/MAX800M are not
short-circuit protected. Shorting V
than power-up transients such as charging a decou-
pling capacitor, destroys the device.
All open-circuit outputs swing between V
rather than V
If long leads connect to the chip inputs, insure that
these leads are free from ringing and other conditions
that would forward bias the chip’s protection diodes.
There are three distinct modes of operation:
Microprocessor Supervisory Circuits
Figure 8. V
12
__________Applications Information
______________________________________________________________________________________
VBATT
CC
V
CC
CC
and VBATT to V
and GND.
MAX800M
CC
MAX691A
MAX693A
MAX800L
Output Supply Voltage
. Decouple this terminal with
OUT
Battery-Backup Input
OUT
Switch
) pin is internally con-
OUT
to ground, other
CC
OUT
OUT
0.1μF
voltage. At
and GND
OUT
will typi-
V
OUT
volt-
CC
VBATT has the same operating voltage range as V
and the battery switchover threshold voltages are typi-
cally ±30mV centered at VBATT, allowing use of a
SuperCap and a simple charging circuit as a backup
source (Figure 9).
If V
above V
until the voltage at VBATT is less than 0.5V above V
For example, with a SuperCap connected to VBATT and
through a diode to V
to 4.9V, the capacitor discharges through V
until VBATT reaches 5.1V typ. Leakage current through
the SuperCap charging diode and the internal power
diode eventually discharges the SuperCap to V
V
and power is lost at V
charges through V
threshold; then the battery-backup mode is initiated and
the current through V
Figure 9. SuperCap or MaxCap on VBATT
CC
1) Normal operating mode with all circuitry powered
2) Battery-backup mode where V
3) Battery-backup mode where V
MAX691A/MAX693A/MAX800L/MAX800M
CC
and VBATT start from 0.1V above the reset threshold
up. Typical supply current from V
only leakage currents flow from the battery.
0.7V below VBATT. All circuitry is powered up
and the supply current from the battery is typically
less than 60µA.
VBATT by at least 0.7V. VBATT supply current is
1µA max.
is above the reset threshold and VBATT is 0.5V
CC
Using SuperCap or MaxCap with the
, current flows to V
+5V
1N4148
0.47F*
* MaxCap
CC
CC
CC
1
, if V
CC
goes to zero.
until VBATT reaches the reset
VBATT
, the SuperCap on VBATT dis-
CC
MAX800M
MAX691A
MAX693A
MAX800L
OUT
quickly changes from 5.4V
GND
V
CC
3
4
and V
CC
V
OUT
is typically within
CC
CC
CC
2
is 35µA while
is less than
OUT
from VBATT
CC
and V
. Also, if
CC
CC
CC
,
.