ADM690AN Analog Devices Inc, ADM690AN Datasheet - Page 5

• Manufacturer Part Number: ADM690AN
• Description: IC SUPERVISOR MPU 4.65 WD 8DIP
• Manufacturer: Analog Devices Inc
• Type: Battery Backup Circuitr

Specifications of ADM690AN

• Rohs Status: RoHS non-compliant
• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 35 ms Minimum
• Voltage - Threshold: 4.65V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Number Of Elements: 1
• Monitored Voltage 1 (typ): 4.75 to 5.5V
• Threshold Voltage 1 (max): 4.73V
• Watchdog Timer: Yes
• Chip Enable Signals: Yes
• Reset Active Time: 70ms
• Package Type: PDIP
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (max): 5.5V
• Reset Threshold Voltage (max): 4.73V
• Reset Threshold Voltage (min): 4.5V
• Family Name: ADM690
• Power Dissipation: 400mW
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Power Fail Detection: Yes
• Mounting: Through Hole
• Pin Count: 8
• Supply Current: 1.95mA
• Battery Backup Switching: Yes
• Manual Reset: No
• Lead Free Status / RoHS Status: Not Compliant

REV. A
Part
Number
ADM690
ADM691
ADM692
ADM693
ADM694
ADM695
CIRCUIT INFORMATION
Battery Switchover Section
The battery switchover circuit compares V
input, and connects V
occurs when V
when V
20 mV of hysteresis prevents repeated rapid switching if V
falls very slowly or remains nearly equal to the battery voltage.
During normal operation with V
ternally switched to V
switch. This switch has a typical on-resistance of 1.5
supply up to 100 mA at the V
used to drive a RAM memory bank which may require instanta-
neous currents of greater than 100 mA. If this is the case then a
bypass capacitor should be connected to V
will provide the peak current transients to the RAM. A capaci-
tance value of 0.1 F or greater may be used.
CC
Figure 1. Battery Switchover Schematic
is 70 mV greater than V
Nominal Reset
Time
50 ms
50 ms or ADJ
50 ms
50 ms or ADJ
200 ms
200 ms or ADJ
CC
is 50 mV higher than V
OUT
OUT
BATT ON
LOW LINE
via an internal PMOS transistor
OSC SEL
to whichever is higher. Switchover
OSC IN
V
V
GND
BATT
OUT
V
OUT
CC
CC
1
2
4
5
terminal. V
3
7
8
6
BATT
higher than V
Nominal V
Reset Threshold
4.65 V
4.65 V
4.4 V
4.4 V
4.65 V
4.65 V
(Not to Scale)
ADM691
ADM693
ADM695
TOP VIEW
as V
BATT
OUT
CC
CC
OUT
as V
. The capacitor
CC
rises. This
to the V
PRODUCT SELECTION GUIDE
BATT
is normally
16
12
15
10
14
13
11
9
CC
PIN CONFIGURATIONS
RESET
RESET
WDO
CE
CE
WDI
PFO
PFI
falls, and
, V
and can
IN
OUT
BATT
CC
Nominal Watchdog
1.6 s
Timeout Period
100 ms, 1.6 s, ADJ
1.6 s
100 ms, 1.6 s, ADJ
1.6 s
100 ms, 1.6 s, ADJ
CC
is in-
–5–
If the continuous output current requirement at V
100 mA or if a lower V
an external PNP pass transistor may be connected in parallel
with the internal transistor. The BATT ON output (ADM691/
ADM693/ADM695) can directly drive the base of the external
transistor.
A 20
during battery backup. This MOSFET has very low input-to-
output differential (dropout voltage) at the low current levels
required for battery back up of CMOS RAM or other low
power CMOS circuitry. The supply current in battery back up
is typically 0.6 A.
The ADM690/ADM691/ADM694/ADM695 operates with
battery voltages from 2.0 V to 4.25 V and the ADM692/ADM693
operates with battery voltages from 2.0 V to 4.0 V. High value
capacitors, either standard electrolytic or the farad size double
layer capacitors, can also be used for short-term memory back
up. A small charging current of typically 10 nA (0.1 A max)
flows out of the V
maintaining rechargeable batteries in a fully charged condition.
This extends the life of the back up battery by compensating
for its self discharge current. Also note that this current poses
no problem when lithium batteries are used for back up since
the maximum charging current (0.1 A) is safe for even the
smallest lithium cells.
If the battery-switchover section is not used, V
connected to GND and V
GND
V
V
OUT
PFI
CC
MOSFET switch connects the V
3
1
2
4
Battery Backup
Switching
Yes
Yes
Yes
Yes
Yes
Yes
(Not to Scale)
ADM690
ADM692
ADM694
TOP VIEW
BATT
CC
terminal. This current is useful for
–V
7
8
6
5
OUT
OUT
WDI
V
RESET
PFO
BATT
should be connected to V
ADM690–ADM695
voltage differential is desired,
Base Drive
Ext PNP
No
Yes
No
Yes
No
Yes
BATT
input to V
BATT
OUT
Chip Enable
Signals
No
Yes
No
Yes
No
Yes
should be
exceeds
CC
OUT
.