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ICL7665SCPAZ

P1-P3P4-P6P7-P9P10-P12P13-P14
10
FN3182.9
July 22, 2013
Combination Low Battery Warning and Low
Battery Disconnect
When using rechargeable batteries in a system, it is
important to keep the batteries from being over discharged.
The circuit shown in Figure 14 provides a low battery
warning and also disconnects the low battery from the rest of
the system to prevent damage to the battery. The OUT1 is
used to shutdown the ICL7663S when the battery voltage
drops to the value where the load should be disconnected.
As long as V
SET1
is greater than 1.3V, OUT1 is low, but
when V
SET1
drops below 1.3V, OUT1 goes high shutting off
the ICL7663S. The OUT2 is used for low battery warning.
When V
SET2
is greater than 1.3V, OUT2 is high and the low
battery warning is on. When V
SET2
drops below 1.3V, OUT2
is low and the low battery warning goes off. The trip voltage
for low battery warning can be set higher than the trip
voltage for shutdown to give advance low battery warning
before the battery is disconnected.
Power Fail Warning and Power-up/Power-down
Reset
Figure 14 shows a power fail warning circuit with
power-up/power-down reset. When the unregulated DC
input is above the trip point, OUT1 is low. When the DC input
drops below the trip point, OUT1 shuts OFF and the power
fail warning goes high. The voltage on the input of the 7805
will continue to provide 5V out at 1A until V
IN
is less than
7.3V, this circuit will provide a certain amount of warning
before the 5V output begins to drop.
The ICL7665S OUT2 is used to prevent a microprocessor
from writing spurious data to a CMOS battery backup
memory by causing OUT2 to go low when the 7805 5V
output drops below the ICL7665S trip point.
FIGURE 13. MULTIPLE SUPPLY FAULT MONITOR
HYST1
V
SET1
V
SET2
HYST2
V+
OUT1 OUT2
274kΩ
R
21
100kΩ
22
POWER
OK
301
R
11
+5V
-15V-5V
MΩ
kΩ
787
kΩ
+5V
1MΩ
1.02MΩ
R
21A
R
21B
22MΩ
49.9kΩ
+5V
+15V
HYST1
SET1 SET2
HYST2
V+
OUT1 OUT2
R
31
R
32
R
12
R
11
R
21
R
22
GND
+
-
LOW BATTERY SHUTDOWN
1MΩ
V+
OUT1
SHUTDOWN V
SET
OUT2
V+
GND
1MΩ
LOW BATTERY WARNING
SENSE
100Ω
+5V
1A
ICL7663S
ICL7665S
FIGURE 14. LOW BATTERY WARNING AND LOW BATTERY DISCONNECT
ICL7665S
11
FN3182.9
July 22, 2013
Simple High/Low Temperature Alarm
Figure 16 illustrates a simple high/low temperature alarm
which uses the ICL7665S with an NPN transistor. The
voltage at the top of R
1
is determined by the V
BE
of the
transistor and the position of R
1
’s wiper arm. This voltage
has a negative temperature coefficient. R
1
is adjusted so
that V
SET2
equals 1.3V when the NPN transistor’s
temperature reaches the temperature selected for the high
temperature alarm. When this occurs, OUT2 goes low. R
2
is
adjusted so that V
SET1
equals 1.3V when the NPN
transistor’s temperature reaches the temperature selected
for the low temperature alarm. When the temperature drops
below this limit, OUT1 goes low.
AC Power Fail and Brownout Detector
Figure 17 shows a circuit that detects AC undervoltage by
monitoring the secondary side of the transformer. The
capacitor, C
1
, is charged through R
1
when OUT1 is OFF.
With a normal 100 VAC input to the transformer, OUT1 will
discharge C
1
once every cycle, approximately every 16.7ms.
When the AC input voltage is reduced, OUT1 will stay OFF,
so that C
1
does not discharge. When the voltage on C
1
reaches 1.3V, OUT2 turns OFF and the power fail warning
goes high. The time constant, R
1
C
1
, is chosen such that it
takes longer than 16.7ms to charge C
1
1.3V.
HYST1
V
SET1
V
SET2
HYST2
V+
OUT1 OUT2
5.86kΩ
130kΩ
BACKUP
BATTERY
7805
5V REGULATOR
UNREGULATED
DC INPUT
1MΩ
22MΩ
2.2MΩ
1MΩ
715kΩ
1MΩ
RESET OR
WRITE
ENABLE
POWER
FAIL
WARNING
470μF
4700μF
ICL7665S
FIGURE 15. POWER FAIL WARNING AND POWERUP/POWERDOWN RESET
ICL7665S
12
FN3182.9
July 22, 2013
Intersil products are manufactured, assembled and tested utilizing ISO9000 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time
without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be
accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
For additional products, see www.intersil.com/en/products.html
HYST1
V
SET1
V
SET2
HYST2
V+
OUT1 OUT2
22kΩ
1.5MΩ
22MΩ
1MΩ
27kΩ
R
4
R
5
V+
1MΩ
R
7
R
2
R
6
ALARM SIGNAL
FOR DRIVING
LEDS, BELLS,
ETC.
LOW TEMPERATURE
LIMIT ADJUST
+-
5V
470kΩ
R
3
TEMPERATURE
SENSOR
(GENERAL PURPOSE
NPN TRANSISTOR)
10kΩ
HIGH
TEMPERATURE
LIMIT ADJUST
R
1
ICL7665S
FIGURE 16. SIMPLE HIGH/LOW TEMPERATURE ALARM
110VAC
60Hz
20V
CENTERED
TAPPED
TRANS.
4700µF
601kΩ
100kΩ
HYST1
V
SET1
V
SET2
HYST2
OUT1 OUT2
1MΩ
1MΩ
7805
5V REGULATOR
5V, 1A
C
1
R
1
1MΩ
+5V
POWER FAIL
WARNING
ICL7665S
FIGURE 17. AC POWER FAIL AND BROWNOUT DETECTOR
ICL7665S
P1-P3P4-P6P7-P9P10-P12P13-P14

ICL7665SCPAZ

Mfr. #:
Buy ICL7665SCPAZ
Manufacturer:
Renesas / Intersil
Description:
Supervisory Circuits W/ANNEAL CMOS OVER/ UNDER V DETECTOR
Lifecycle:
New from this manufacturer.
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