ICL7665S_06 Datasheet, PDF (10/14 Pages) Intersil Corporation – CMOS Micropower Over/Under Voltage Detector

ICL7665S
274kΩ
R_21A
+5V
+15V
1.02MΩ
R_21B
V+
HYST1 HYST2
R₂₁
49.9kΩ
R₁₁
V_SET1 V_SET2
OUT1 OUT2
+5V
22
100kΩ
MΩ
301 787
kΩ kΩ +5V
-5V -15V 1MΩ
POWER
OK
FIGURE 13. MULTIPLE SUPPLY FAULT MONITOR
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. 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. 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 Powerup/Powerdown
Reset
Figure 15 shows a power fail warning circuit with
powerup/powerdown 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.
R₃₁
+ _R21
-
R₁₁
R₃₂
V+
HYST1
HYST2
1MΩ
+5V
100Ω
1A
V+
OUT1
OUT2
ICL7665S
SET1
SET2
OUT1 GND OUT2
R₂₂
R₁₂
V+
1MΩ
ICL7663S ^SENSE
SHUTDOWN
GND
V_SET
LOW BATTERY SHUTDOWN
LOW BATTERY WARNING
FIGURE 14. LOW BATTERY WARNING AND LOW BATTERY DISCONNECT
10
FN3182.8
April 5, 2006