7-173

ICL8211, ICL8212

Since there is no internal compensation in the ICL8212 it is

necessary to use a large capacitor across the output to

prevent oscillation.

Zener voltages from 2V to 30V may be programmed and typ-

ical impedance values between 300

µA and 25µA will range

from 4

Ω to 7Ω. The knee is sharper and occurs at a signifi-

cantly lower current than other similar devices available.

FIGURE 32. CONSTANT CURRENT SOURCE APPLICATIONS

FIGURE 33. PROGRAMMABLE ZENER VOLTAGE REFERENCE

Precision Voltage Regulator (Figure 34)

The ICL8212 may be used as the controller for a highly sta-

ble series voltage regulator. The output voltage is simply pro-

the ICL8212 is uncompensated internally.

FIGURE 34. PRECISION VOLTAGE REGULATOR

1

2

3

4

8

7

6

5

1

2

3

4

8

7

6

5

I

=

OR

V+

I

I = 25

µA (ICL8212)

I = 130

µA (ICL8211)

ICL

8212

OUT

V+

V+

500K

150K

+

6

5

4

3

2

1

0

0.01

0.1

1.0

10

100

SUPPLY CURRENT (mA)

1

2

3

4

8

7

6

5

V+

V+

UNREG-

ULATED

DC SUPPLY

ICL8212

x 1.15V

This regulator may be used with lower input voltages than

most other commercially available regulators and also con-

sumes less power for a given output control current than any

commercial regulator. Applications would therefore include

battery operated equipment especially those operating at

low voltages.

High Supply Voltage Dump Circuit (Figure 35)

In many circuit applications it is desirable to remove the

power supply in the case of high voltage overload. For

circuits consuming less than 5mA this may be achieved

using an ICL8211 driving the load directly. For higher load

currents it is necessary to use an external pnp transistor or

darlington pair driven by the output of the ICL8211.

provides optional voltage hysteresis if so desired.

FIGURE 35. HIGH VOLTAGE DUMP CIRCUITS

Frequency Limit Detector (Figure 36)

Simple frequency limit detectors providing a GO/NO-GO out-

put for use with varying amplitude input signals may be con-

veniently implemented with the ICL8211/8212. In the

application shown, the first ICL8212 is used as a zero cross-

results in a slow output positive ramp. The negative range is

teresis so that under all circumstances the second ICL8212

the desired output polarities for low and high input frequen-

cies, either an ICL8211 or an ICL8212 may be used as the

output driver.

This circuit is sensitive to supply voltage variations and

should be used with a stabilized power supply. At very low

frequencies the output will switch at the input frequency.

Switch Bounce Filter (Figure 37)

Single pole single throw (SPST) switches are less costly and

more available than single pole double throw (SPDT) switches.

1

2

3

4

8

7

6

5

ICL8211

V-

V+

(a)

1

2

3

4

8

7

6

5

ICL8211

V-

V+

CIRCUIT

BEING

PROTECTED

V-

V+

(b)

CIRCUIT

BEING

PROTECTED

V-

V+