ICL8212CBA HARRIS [Harris Corporation], ICL8212CBA Datasheet - Page 14

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ICL8212CBA

Manufacturer Part Number
ICL8212CBA
Description
Programmable Voltage Detectors
Manufacturer
HARRIS [Harris Corporation]
Datasheet

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ICL8212CBA
Manufacturer:
INTERSIL
Quantity:
13 382
SPST switches range from push button and slide types to cal-
culator keyboards. A major problem with the use of switches is
the mechanical bounce of the electrical contacts on closure.
Contact bounce times can range from a fraction of a millisec-
ond to several tens of milliseconds depending upon the switch
type. During this contact bounce time the switch may make and
break contact several times. The circuit shown in Figure 37 pro-
vides a rapid charge up of C
voltage (V
charge of C
stant of R
the output as terminal #4 of the ICL8211/8212 will be a single
transition of state per desired switch closure
INPUT
R
R
V+
2
3
INPUT
1.15V
1.15V
A
B
C
R
R
1
R
1
4
1
1
1
C
) on a switch closure and a corresponding slow dis-
1
R
FIGURE 37. SWITCH BOUNCE FILTER
1
100
2
on a switch break. By proportioning the time con-
C
to approximately the manufacturer’s bounce time
1
1
2
3
4
ON TIME #2
1
2
3
4
ICL8212
R
1
3
to close to the positive supply
ICL8211
ICL8212
OR
8
7
6
5
FIGURE 36. FREQUENCY LIMIT DETECTOR
R
8
7
6
5
4
A
TIME CONSTANT R
VARY R
VARY R
C
2
R
ICL8211, ICL8212
5
1
4
R
FOR OPTION ZERO CROSSING DETECTION
TO SET DETECTION FREQUENCY
L
R
6
V+
V
O
7-174
1
2
3
4
3
C
Low Voltage Power Disconnect (Figure 38)
There are some classes of circuits that require the power
supply to be disconnected if the power supply voltage falls
below a certain value. As an example, the National LM199
precision reference has an on chip heater which malfunc-
tions with supply voltages below 9V causing an excessive
device temperature. The ICL8212 may be used to detect a
power supply voltage of 9V and turn the power supply off to
the LM199 heater section below that voltage.
For further applications, see AN027 “Power Supply Design
using the ICL8211 and ICL8212.”
500k
56k
2
FIGURE 38. LOW VOLTAGE POWER SUPPLY DISCONNECT
< R
OFF
ICL8212
ON
4
C
2
R
7
C
1
2
3
4
3
8
7
6
5
F
ICL8212
INDETERMINATE
BELOW F
O
R
7
B
FREQUENCY
C
3
O
8
7
6
5
1
2
3
4
3.9k
4.7k
ICL8211
ICL8212
OR
#3
8
7
6
5
REFERENCE
R
ON
OFF
OUTPUT
6
OUTPUT
LM199
V-

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