Datasheet ICL8211MTY, ICL8212CBA, ICL8212CPA, ICL8212CTY, ICL8212MTY Datasheet (Harris Semiconductor)

SEMICONDUCTOR

ICL8211, ICL8212

April 1994

Features

• High Accuracy Voltage Sensing and Generation

• Internal Reference 1.15V Typical

• Low Sensitivity to Supply Voltage and Temperature
Variations

• Wide Supply Voltage Range Typ. 1.8V to 30V

• Essentially Constant Supply Current Over Full Supply
Voltage Range

• Easy to Set Hysteresis Voltage Range

• Defined Output Current Limit ICL8211

• High Output Current Capability ICL8212

Applications

• Low Voltage Sensor/Indicator

• High Voltage Sensor/Indicator

• Nonvolatile Out-of-Voltage Range Sensor/Indicator

• Programmable Voltage Reference or Zener Diode

• Series or Shunt Power Supply Regulator

• Fixed Value Constant Current Source

Programmable Voltage Detectors

Description

The Harris ICL8211/8212 are micropower bipolar monolithic
integrated circuits intended primarily for precise voltage
detection and generation. These circuits consist of an
accurate voltage reference, a comparator and a pair of
output buffer/drivers.

Specifically, the ICL8211 provides a 7mA current limited out­put sink when the voltage applied to the ‘THRESHOLD’
terminal is less than 1.15V (the internal reference). The
ICL8212 requires a voltage in excess of 1.15V to switch its
output on (no current limit). Both devices have a low current
output (HYSTERESIS) which is switched on for input
voltages in excess of 1.15V. The HYSTERESIS output may
be used to provide positive and noise free output switching
using a simple feedback network.

Ordering Information

TEMPERATURE

PART NUMBER

ICL8211CPA 0oC to +70oC 8 Lead Plastic DIP
ICL8211CBA 0oC to +70oC 8 Lead SOlC (N)
ICL8211CTY 0oC to +70oC 8 Pin Metal Can
ICL8211MTY

(Note 1)
ICL8212CPA 0oC to +70oC 8 Lead Plastic DIP
ICL8212CBA 0oC to +70oC 8 Lead SOlC (N)
ICL8212CTY 0oC to +70oC 8 Pin Metal Can
ICL8212MTY

(Note 1)

NOTE:

1. Add /883B to part number if 883B processing is required

RANGE PACKAGE

-55oC to +125oC 8 Pin Metal Can

-55oC to +125oC 8 Pin Metal Can

Pinouts

ICL8211 (PDIP, SOIC)

TOP VIEW

NC

1

HYSTERESIS

THRESHOLD

OUTPUT

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright

© Harris Corporation 1992

2
3
4

8

V+

7

NC

6

NC

5

GROUND

THRESHOLD

OUTPUT

7-161

ICL8211 (CAN)

1

2

3

NC

TOP VIEW

HYSTERESIS

8

4

GROUND

V+

7

6

NC

NC

5

File Number

3184.1

Functional Diagram

VOLTAGE REFERENCE COMPARATOR OUTPUT BUFFERS

ICL8211, ICL8212

8

V+

R1

20MΩ

Q1

Q7

Q2

Q3

Q5

1.15V

Q23

Q4

Q6

V

REF

R3
360kΩ

Q16

Q12

Q14

Q15

Q13

Q17

R4
1MΩ

Q18

X X X X

Q19

R5

4.5kΩ

2

HYST

3

THRESHOLD

Q8

R2

30kΩ

X X X X X X

Q9

ICL8211 OPTION
ICL8212 OPTION

Q10

Q11

Q20

R6
100kΩ

Q21

4

5

OUTPUT

GROUND

7-162

Specifications ICL8211, ICL8212

Absolute Maximum Ratings Thermal Information

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +30V

Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +30V

Hysteresis Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.5V to -10V

Threshold Input Voltage . . . . . . . . . . . . .+30V to -5V with respect to

GROUND and +0V to -30V with respect to V+

Current into Any Terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 30mA

CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation
of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.

Operating Conditions

Operating Temperature Range

ICL8211M/8212M . . . . . . . . . . . . . . . . . . . . . . . . -55oC to +125oC

ICL8211C/8212C . . . . . . . . . . . . . . . . . . . . . . . . . . .0oC to +70oC

Thermal Resistance θ

JA

θ

JC

Plastic DIP Package . . . . . . . . . . . . . . . . 150oC/W -

Plastic SOIC Package. . . . . . . . . . . . . . . 180oC/W -

Metal Can . . . . . . . . . . . . . . . . . . . . . . . . 156oC/W 68oC/W

Lead Temperature (Soldering, 10s). . . . . . . . . . . . . . . . . . . . . 300oC

(SOIC - Lead Tips Only)

Current into Any Terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 30mA

Storage Temperature Range. . . . . . . . . . . . . . . . . .-65oC to +150oC

Electrical Specifications V+ = 5V, T

= +25oC Unless Otherwise Specified

A

PARAMETER SYMBOL TEST CONDITIONS

Supply Current I+ 2.0 < V+ < 30 V

Threshold Trip Voltage V

Threshold Voltage
Disparity Between
Output & Hysteresis
Output

Guaranteed Operating

V

SUPPLY

Supply Voltage Range

Minimum Operating

V

SUPPLY

Supply Voltage Range

V

THP

I

TH

OUT

V

OUT

I

OUT

I

HYST

V

OUT

V

HYST

= 4mA

= 2V

= 4mA

= 7mA
= 2V

= 3V
+25oC (Note 3) 2.0 - 30 2.0 - 30 V
0oC to +70oC (Note 3) 2.2 - 30 2.2 - 30 V
+25oC - 1.8 - - 1.8 - V
+125oC - 1.4 - - 1.4 - V

-55oC - 1.5 - - 2.5 - V

Threshold Voltage Tem-

∆VTH/∆TI

OUT

= 4mA, V

= 2V - ± 200 - - ± 200 - ppm/oC

OUT

perature Coefficient
Variation of Threshold

∆VTH/∆V+ ∆V+ = 10% at V+ = 5V - 1.0 - - 1.0 - mV
Voltage with Supply
Voltage

Threshold Input Current I

TH

VTH = 1.15V - 100 250 - 100 250 nA
VTH = 1.00V - 5 - - 5 - nA

Output Leakage Current I

Output Saturation

V

OLK

SAT

V

= 30V VTH = 0.9V -----10µA

OUT

V

= 5V VTH = 0.9V -----1µA

OUT

I

= 4mA VTH = 0.9V - 0.17 0.4 - - - V

OUT

Voltage

Max Available Output
Current

Hysteresis Leakage
Current

I

OH

I

LHYS

(Notes 3 & 4)
V

= 5V

OUT

V+ = 10V,
V

= GND

HYST

ICL8211 ICL8212

UNITSMIN TYP MAX MIN TYP MAX

= 1.3V 10 22 40 50 110 250 µA

TH

VTH = 0.9V 50 140 250 10 20 40 µA
V+ = 5V 0.98 1.15 1.19 1.00 1.15 1.19 V
V+ = 2V 0.98 1.145 1.19 1.00 1.145 1.19 V
V+ = 30V 1.00 1.165 1.20 1.05 1.165 1.20 V

- -0.8 - - -0.5 - mV

VTH = 1.3V - - 10 - - - µA

VTH = 1.3V - - 1 - - - µA

VTH = 1.3V ----0.17 0.4 V
VTH = 0.9V 4 7.0 12 - - - mA
VTH = 1.3V - - - 15 35 - mA
VTH = 1.0V - - 0.1 - - 0.1 µA

7-163

ICL8211, ICL8212

Electrical Specifications V+ = 5V, T

= +25oC Unless Otherwise Specified (Continued)

A

ICL8211 ICL8212

PARAMETER SYMBOL TEST CONDITIONS

Hysteresis Sat Voltage V

HYS(MAX)IHYST

= -7µA,

VTH = 1.3V - -0.1 -0.2 - -0.1 -0.2 V

UNITSMIN TYP MAX MIN TYP MAX

measured with
respect to V+

Max Available

I

HYS (MAX)

VTH = 1.3V -15 -21 - -15 -21 - µA

Hysteresis Current

Electrical Specifications ICL8211MTY/8212MTY V+ = 5V, T

= -55oC to +125oC

A

ICL8211 ICL8212

PARAMETER SYMBOL TEST CONDITIONS

UNITSMIN TYP MAX MIN TYP MAX

Supply Current I+ 2.8 < V+ < 30 ------ -

= 1.3V - - 100 - 350 350 µA

V

T

VT = 0.8V - - 350 - 100 100 µA

Threshold Trip Voltage V

Guaranteed Operating

V

SUPPLY

I

TH

OUT

V

OUT

= 2mA

= 2V

V+ = 2.8V 0.80 - 1.30 0.80 - 1.30 V
V+ = 30V 0.80 - 1.30 0.80 - 1.30 V

(Note 5) 2.8 - 30 2.8 - 30 V

Supply Voltage Range
Threshold Input Current I
Output Leakage Current I

TH

OLK

VTH = 1.15V - - 400 - - 400 nA
V

= 30V VTH = 0.8V -----20µA

OUT

VTH = 1.3V - - 20 - - - µA

Output Saturation
Voltage

Max Available Output
Current

Hysteresis Leakage
Current

Hysteresis Saturation
Voltage

V

SAT

I

OH

I

(Notes 3 & 4)
V

I

LHYS

V+ = 10V
V

V

HYS(MAX)IHYST

measured with

= 3mA VTH = 0.8V - - 0.5 - - - V

OUT

VTH = 1.3V -----0.5V
VTH = 0.8 3 - 15 - - - mA

= 5V

OUT

VTH = 1.3V - - - 9 - - mA
VTH = 0.8V - - 0.2 - - 0.2 µA

= GND

HYST

= -7µA

VTH = 1.3V - - 0.3 - - 0.3 V

respect to V+

Max Available

I

HYS (MAX)

VTH = 1.3V 10 - - 10 - - µA

Hysteresis Current

NOTES:

1. The maximum output current of the ICL8211 is limited by design to 15mA under any operating conditions. The output voltage may be

sustained at any voltage up to +30V as long as the maximum power dissipation of the device is not exceeded.

2. The maximum output current of the ICL8212 is not defined. And systems using the ICL8212 must therefore ensure that the output current

does not exceed 30mA and that the maximum power dissipation of the device is not exceeded.

3. Threshold Trip Voltage is 0.80V(min) to 1.30V(mas). At I

OUT

= 3mA.

7-164

ICL8211, ICL8212

Typical Performance Curves

10,000

TA = +25oC
V+ = +10V

1,000

ICL8211 OR ICL8212

100

THRESHOLD INPUT CURRENT (nA)

10

0.0 1.1 1.15 1.2 2.0 3.0 6.0 8.0 10.0
THRESHOLD VOLTAGE (VTH)

(IRREGULAR SCALE)

(ICL8211 and ICL8212)

FIGURE 1. THRESHOLD INPUT CURRENT AS A FUNCTION OF

THRESHOLD VOLTAGE

Typical Performance Curves

150

125

100

75

TA = +25oC
OUTPUTS OPEN CIRCUIT

(ICL8211 ONLY)

VTH = 0.9V

0

V+ = +5V
V

= 1.2V

TH

V

= 4.5V

-5

HYS

(OR -0.5V WITH RESPECT

TO V+ SUPPLY)

-10

-20

-25
ICL8211 OR ICL8212

-30

HYSTERESIS OUTPUT CURRENT (µA)

-40 -20 0 +20 +40 +60 +80

o

TEMPERATURE (

C)

FIGURE 2. HYSTERESIS OUTPUT SATURATION CURRENT AS

A FUNCTION OF TEMPERATURE

150

125

100

75

TA = +25oC
V+ = +5V
OUTPUTS OPEN
CIRCUIT

50

SUPPLY CURRENT (µA)

25

VTH = 1.3V

0102030

SUPPLY VOLTAGE

FIGURE 3. SUPPLY CURRENT AS A FUNCTION OF SUPPLY

VOLTAGE

150

125

100

75

50

SUPPLY CURRENT (µA)

25

0

-55 -25 +5 +35 +65 +95 +125

VTH = 0.9V

VTH = 1.3V

TEMPERATURE

o

C

FIGURE 5. SUPPLY CURRENT AS A FUNCTION OF TEMPERA-

TURE

50

SUPPLY CURRENT (µA)

25

0

0.0 1.0 1.1 1.15 1.2 2.0 4.0
THRESHOLD VOLTAGE (V

(IRREGULAR SCALE)

)

TH

FIGURE 4. SUPPLY CURRENT AS A FUNCTION OF THRESH-

OLD VOLTAGE

12

10

8

6

OUTPUT

4

OUTPUT CURRENT (mA)

2

0

1.12 1.13 1.14 1.15 1.16 1.17 1.18
THRESHOLD VOLTAGE

TA = +25oC
V+ = +5V
VO = 0.5V

= V+ - 0.25V

V

HYS

HYSTERESIS
OUTPUT

8mV

0

-5

-10

-15

-20

-25

-30

HYSTERESIS OUTPUT CURRENT (µA)

FIGURE 6. OUTPUT SATURATION CURRENTS AS A FUNC-

TION OF THRESHOLD VOLTAGE

7-165

ICL8211, ICL8212

Typical Performance Curves

OUTPUT

1.15

1.14
HYSTERESIS OUTPUT

THRESHOLD VOLTAGE

1.13

-55 -25 +5 +35 +65 +95 +125

V+ = +5V
I

= 1mA, V

O

= -7µA, V

I

HYS

TEMPERATURE (

(ICL8211 ONLY) (Continued)

= +5V

OUT

= 0V

HST

o

C)

FIGURE 7. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST

ON” AS A FUNCTION OF TEMPERATURE

8

7

1.18
IO = 4mA, VO = 1V

I

= -7µA, V

HYS

1.17

1.16

1.15

THRESHOLD VOLTAGE

1.14

1.13

1 2 3 4 5 10 20 30 4050 100

= (V+ -2) V

HYS

OUTPUT

HYSTERESIS OUTPUT

SUPPLY VOLTAGE

FIGURE 8. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST

ON” AS A FUNCTION OF SUPPLY VOLTAGE

12

TA = +25oC
V+ = +5V

9

VTH = 1.0V

6

6

OUTPUT CURRENT (mA)

5

-55 -25 +5 +35 +65 +95 +125
TEMPERATURE (

V+ = +5V
VTH = 1.1V
VO = 1.0V

o

C)

FIGURE 9. OUTPUT SATURATION CURRENT AS A FUNCTION

OF TEMPERATURE

0

-5

-10

-15

-20

-25

-30

-35

HYSTERESIS OUTPUT CURRENT (µA)

-40

VT = 1.143V

VT = 1.144V

VT = 1.18V

-10.00 -1.00 -0.10 -0.01
HYSTERESIS OUTPUT VOLTAGE

FIGURE 11. HYSTERESIS OUTPUT CURRENT AS A FUNCTION OF HYSTERESIS OUTPUT VOLTAGE

3

OUTPUT CURRENT (mA)

0

0.1 1.0 10.0 100.0

VTH = 1.147V

VTH = 1.152V

OUTPUT VOLTAGE

FIGURE 10. OUTPUT CURRENT AS A FUNCTION OF OUTPUT

VOLTAGE

TA = +25oC
V+ = +10V

7-166

ICL8211, ICL8212

Typical Performance Curves

150

TA = +25oC
OUTPUTS OPEN CIRCUIT

125

100

75

50

SUPPLY CURRENT (µA)

25

0

0 102030

VTH = 1.3V

VTH = 0.9V

SUPPLY VOLTAGE

(ICL8212 ONLY)

FIGURE 12. SUPPLY CURRENT AS A FUNCTION OF SUPPLY

VOLTAGE

150

V+ = 5V
OUTPUTS

125

OPEN
CIRCUIT

100

75

50

SUPPLY CURRENT - I+ (µA)

25

0

-55 -25 +5 +35 +65
TEMPERATURE (oC)

VTH = 1.3V

VTH = 0.9V

+95

+125

FIGURE 14. SUPPLY CURRENT AS A FUNCTION OF TEMPER-

ATURE

150

TA = +25oC
V+ = +5V

125

OUTPUTS OPEN CIRCUIT

100

75

50

SUPPLY CURRENT - I+ (µA)

25

0

0.0 1.0 1.1 1.15 1.2 2.0 4.0
THRESHOLD VOLTAGE (VTH)

(IRREGULAR SCALE)

FIGURE 13. SUPPLY CURRENT AS A FUNCTION OF THRESH-

OLD VOLTAGE

30

25

TA = +25oC

20

15

10

OUTPUT CURRENT (mA)

5

0

1.14 1.15 1.16 1.17 1.18 1.19 1.20

OUTPUT

THRESHOLD VOLTAGE

V+ = 5V

= 4V

V

OUT

V

= V+ -0.25V

HYS

HYSTERESIS OUTPUT

0

-5

-10

-15

-20

-25

HYSTERESIS OUTPUT CURRENT (µA)

-30

FIGURE 15. OUTPUT SATURATION CURRENTS AS A FUNC-

TION OF THRESHOLD VOLTAGE

1.17
IO = 1mA, V

= -7µA, V

I

HYS

1.16

1.15

THRESHOLD VOLTAGE

1.14

-55 -25 +5 +35 +65 +95 +125

= 5V

OUT

= 0V

HYS

BOTH OUTPUT AND
HYSTERESIS OUTPUT

TEMPERATURE (

o

C)

FIGURE 16. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST

ON” AS A FUNCTION OF TEMPERATURE

1.18

1.17

1.16

BOTH OUTPUT AND

1.15

THRESHOLD VOLTAGE

1.14

1.13
1 2 3 4 5 10 20 30 4050 100

HYSTERESIS OUTPUT

TA = +25oC

= 4mA, V

I

OUT

= -7µA, V

I

HYS

SUPPLY VOLTAGE

OUT
HYS

= 1V

= (V+ -2) V

FIGURE 17. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST

ON” AS A FUNCTION OF SUPPLY VOLTAGE

7-167

ICL8211, ICL8212

Typical Performance Curves

(ICL8212 ONLY) (Continued)

0.6

0.5

0.4

0.3

0.2

0.1

OUTPUT SATURATION VOLTAGE

0

-55 -25 +5 +35 +65 +95 +125

FIGURE 18. OUTPUT SATURATION VOLTAGE AND CURRENT

AS A FUNCTION OF TEMPERATURE

40

TA = +25oC
V+ = +5V

30

OUTPUT SAT.
CURRENT

(VO = 4.0V)

VOLTAGE SAT.
CURRENT
(I

= 10mA)

O

V+ = +5V
V

TEMPERATURE (oC)

VTH =1.25V

TH

= 1.2V

Detailed Description

The ICL8211 and ICL8212 use standard linear bipolar
integrated circuit technology with high value thin film
resistors which define extremely low value currents.

Components Q
accurate voltage reference of 1.15V. This reference voltage
is close to the value of the bandgap voltage for silicon and is
highly stable with respect to both temperature and supply
voltage. The deviation from the bandgap voltage is
necessary due to the negative temperature coefficient of the
thin film resistors (-5000 ppm per

Components Q
current source; Q
mirror. Q

8

current mirror, the collector currents of Q
to be equal and it can be shown that the collector current in
Q

and Q9 is

8

or approximately 1µA at +25

Where k = Boltzman’s Constant

q = Charge on an Electron

and T = Absolute Temperature inoK

through Q10 and R1, R2 and R3 set up an

1

o

C).

through Q9 and R2 make up a constant

2

and Q3 are identical and form a current

2

has 7 times the emitter area of Q9, and due to the

and Q9 are forced

8

IC (Q8 or Q9) =

1

R2 q

o

C

kT

x

In7

20

VTH = 1.158V

10

OUTPUT CURRENT (mA)

0

0.1 1.0 10.0 30.0 100.0
OUTPUT VOLTAGE

VTH = 1.153V

FIGURE 19. OUTPUT CURRENT AS A FUNCTION OF OUTPUT

VOLTAGE

0

-5

-10

-15

-20

-25

-30

-35

HYSTERESIS OUTPUT CURRENT (µA)

-40

-10.00 -1.00 -0.10 -0.01

VT = 1.152V

VT= 1.153V

VT = 1.18V

TA = +25oC
V+ = +10V

HYSTERESIS OUTPUT VOLTAGE

FIGURE 20. HYSTERESIS OUTPUT CURRENT AS A FUNCTION

OF HYSTERESIS OUTPUT VOLTAGE

Transistors Q
and Q

9

, Q6, and Q7 assure that the VCE of Q3, Q4,

5

remain constant with supply voltage variations. This

ensures a constant current supply free from variations.
The base current of Q

provides sufficient start up current for

1

the constant source; there being two stable states for this
type of circuit - either ON as defined above, or OFF if no
start up current is provided. Leakage current in the transis­tors is not sufficient in itself to guarantee reliable startup.

Q

is matched to Q3 and Q2; Q10 is matched to Q9. Thus the

4

IC and V

of Q10 are identical to that of Q9 or Q8. To

BE

generate the bandgap voltage, it is necessary to sum a
voltage equal to the base emitter voltage of Q

to a voltage

9

proportional to the difference of the base emitter voltages of
two transistors Q

Thus 1.5 = VBE(Q9 or Q10) +

which provides:

and Q9 operating at two current densities.

8

R

3

R

2

R

3

= 12 (approximately.)

R

2

kT

x

q

The total supply current consumed by the voltage reference
section is approximately 6µA at room temperature. A voltage
at the THRESHOLD input is compared to the reference 1.15V
by the comparator consisting of transistors Q

through Q17.

11

The outputs from the comparator are limited to two diode
drops less than V+ or approximately 1.1V. Thus the base cur­rent into the hysteresis output transistor is limited to about
500nA and the collector current of Q

In the case of the ICL8211, Q
times the emitter area of Q

20

to 100µA.

19

is proportioned to have 70

21

thereby limiting the output

current to approximately 7mA, whereas for the ICL8212

7-168

ICL8211, ICL8212

almost all the collector current of Q19 is available for base
drive to Q

, resulting in a maximum available collector

21

current of the order of 30mA. It is advisable to externally limit
this current to 25mA or less.

Applications

The ICL8211 and ICL8212 are similar in many respects, espe­cially with regard to the setup of the input trip conditions and
hysteresis circuitry. The following discussion describes both
devices, and where differences occur they are clearly noted.

General Information

Threshold Input Considerations

Although any voltage between -5V and V+ may be applied to
the THRESHOLD terminal, it is recommended that the
THRESHOLD voltage does not exceed about +6V since
above that voltage the threshold input current increases
sharply. Also, prolonged operation above this voltage will
lead to degradation of device characteristics.

The outputs change states with an input THRESHOLD
voltage of approximately 1.15V. Input and output waveforms
are shown in Figure 21 for a simple 1.15V level detector.

R

L1

V+

(V+ MUST BE
EQUAL OR
EXCEED 1.8V)

V

HYST

V

O

INPUT VOLTAGE
(RECOMMENDED
RANGE -5 TO +5V)

V

TH

1
2
3
4

8
7
6
5

as TTL or CMOS using a single pullup resistor. There is a
guaranteed TTL fanout of 2 for the ICL8211 and 4 for the
ICL8212.

A principal application of the ICL8211 is voltage level
detection, and for that reason the OUTPUT current has been
limited to typically 7mA to permit direct drive of an LED
connected to the positive supply without a series current
limiting resistor.

On the other hand the ICL8212 is intended for applications
such as programmable zener references, and voltage
regulators where output currents well in excess of 7mA are
desirable. Therefore, the output of the ICL8212 is not current
limited, and if the output is used to drive an LED, a series
current limiting resistor must be used.

In most applications an input resistor divider network may be
used to generate the 1.15V required for V

. For high accu-

TH

racy, currents as large as 50µA may be used, however for
those applications where current limiting may be desirable,
(such as when operating from a battery) currents as low as
6mA may be considered without a great loss of accuracy.
6mA represents a practical minimum, since it is about this
level where the device’s own input current becomes a signifi­cant percentage of that flowing in the divider network.

V+

1
2

V

TH

3
4

8
7
6
5

PULLUP RESISTOR

CMOS OR
TTL GATES

R

L2

1.15V

V+

0V

V+

0V

V

O2

0

ICL8211 OUTPUT

ICL8212 OUTPUT

V

O1

FIGURE 21. VOLTAGE LEVEL DETECTION

The HYSTERESIS output is a low current output and is
intended primarily for input threshold voltage hysteresis
applications. If this output is used for other applications it is
suggested that output currents be limited to 10µA or less.

The regular OUTPUT’s from either the ICL8211 or ICL8212
may be used to drive most of the common logic families such

FIGURE 22. OUTPUT LOGIC INTERFACE

INPUT

R

2

V

R

1

V-

1
2

TH

3
4

V+

8
7
6
5

FIGURE 23. INPUT RESISTOR NETWORK CONSIDERATIONS

Case 1. High accuracy required, current in resistor network

unimportant Set I = 50µA for V

= 1.15V ∴ R1→

TH

20kΩ

Case 2. Good accuracy required, current in resistor network

important Set I = 7.5µA for V

= 1.15V ∴ R1→

TH

150kΩ

7-169

ICL8211, ICL8212

INPUT

INPUT

VOLTAGE

V-

R

2

R

1

1
2
3
4

V+

8
7
6
5

Input voltage to change to output states

+ R2)

(R

1

=

x 1.15V

R

1

FIGURE 24. RANGE OF INPUT VOLTAGE GREATER THAN

+1.15 VOLTS

Setup Procedures For Voltage Level Detection

Case 1. Simple voltage detection no hysteresis
Unless an input voltage of approximately 1.15V is to be

detected, resistor networks will be used to divide or multiply
the unknown voltage to be sensed. Figure 25 shows
procedures on how to set up resistor networks to detect
INPUT VOLTAGES of any magnitude and polarity.

V

REF (+VE)

R

R

1

2

Range of input voltage less than +1.15V
Input voltage to change the output states

FIGURE 25. INPUT RESISTOR NETWORK SETUP

PROCEDURES

MAY BE ANY STABLE VOLTAGE
VOLTAGE REFERENCE
GREATER THAN 1.15V

1
2
3
4

+ R2) x 1.15

(R

1

=

R

1

V+

8
7
6
5

R2V

REF

­R

1

For supply voltage level detection applications the input
resistor network is connected across the supply terminals as
shown in Figure 26.

V+

R

2

R

1

1
2
3
4

8
7
6
5

INPUT VOLTAGE

OR

SUPPLY VOLTAGE

V

O

FIGURE 26. COMBINED INPUT AND SUPPLY VOLTAGES

Case 2. Use of the HYSTERESIS function

The disadvantage of the simple detection circuits is that
there is a small but finite input range where the outputs are
neither totally ‘ON’ nor totally ‘OFF’. The principle behind
hysteresis is to provide positive feedback to the input trip
point such that there is a voltage difference between the
input voltage necessary to turn the outputs ON and OFF.

The advantage of hysteresis is especially apparent in
electrically noisy environments where simple but positive
voltage detection is required. Hysteresis circuitry , however , is
not limited to applications requiring better noise performance
but may be expanded into highly complex systems with
multiple voltage level detection and memory applications­refer to specific applications section.

There are two simple methods to apply hysteresis to a circuit
for use in supply voltage level detection. These are shown in
Figure 27.

The circuit of Figure 27A requires that the full current flowing
in the resistor network be sourced by the HYSTERESIS out­put, whereas for circuit Figure 27B the current to be sourced
by the HYSTERESIS output will be a function of the ratio of
the two trip points and their values. For low values of hyster­esis, circuit Figure 27B is to be preferred due to the offset
voltage of the hysteresis output transistor.

A third way to obtain hysteresis (ICL8211 only) is to connect
a resistor between the OUTPUT and the THRESHOLD
terminals thereby reducing the total external resistance
between the THRESHOLD and GROUND when the
OUTPUT is switched on.

Practical Applications

Low Voltage Battery Indicator (Figure 28)

This application is particularly suitable for portable or remote
operated equipment which requires an indication of a depleted
or discharged battery. The quiescent current taken by the sys­tem will be typically 35µA which will increase to 7mA when the
lamp is turned on. R

Nonvolatile Low Voltage Detector (Figure 29)

In this application the high trip voltage V
above the normal supply voltage range. On power up the
initial condition is A. On momentarily closing switch S
operating point changes to B and will remain at B until the
supply voltage drops below VTR1, at which time the output
will revert to condition A. Note that state A is always retained
if the supply voltage is reduced below V
volts) and then raised back to V

Nonvolatile Power Supply Malfunction Recorde
(Figure 30 and Figure 31)

In many systems a transient or an extended abnormal (or
absence of a) supply voltage will cause a system failure.
This failure may take the form of information lost in a volatile
semiconductor memory stack, a loss of time in a timer or
even possible irreversible damage to components if a supply
voltage exceeds a certain value.

It is, therefore, necessary to be able to detect and store the
fact that an out-of-operating range supply voltage condition
has occurred, even in the case where a supply voltage may

will provide hysteresis if required.

3

is set to be

TR2

(even to zero

TR1

.

NOM

the

1

7-170

ICL8211, ICL8212

V+

R

3

1

R

2

R

1

2
3
4

8
7
6
5

V

O

R

150kΩ

2

R

3

(NOTE 1)

1

ICL8211

2
3
4

8

LED

7

LAMP

6
5

Low trip voltage

V

High trip voltage
V

R

Q

R

S

R

P

Low trip voltage

V

TR1

High trip voltage
V

TR2

=

TR1

=

TR2

1
2
3
4

FIG 7

=

(RP + RQ)

=

(R

+ R2) x 1.15 + 0.1V

1

(R1 + R2 + R3)

R

1

FIGURE 27A.

RQR

S

(RQ + RS)

x 1.15V

R

P

FIGURE 27B.

+ R

R

8
7
6
5

1

P

x 1.15V

1

x

R

x 1.15V

P

volts

NOTE 1. R

OPTIONAL

3

FIGURE 28. LOW VOLTAGE BATTERY INDICATOR

V+

S

R

R

V

O

R

1

3

2

1

1
2
3
4

8
7

R

L

6
5

V+

OUTPUT

FIGURE 29A.

OFF

ON

ICL8211 OUTPUT STATE

V

TR1

SUPPLY VOLTAGE

V

TR2

FIGURE 27C.

FIGURE 27. TWO ATERNATIVE VOLTAGE DETECTION

CIRCUITS EMPLOYING HYSTERESIS TO
PROVIDE PAIRS OF WELL DEFINED TRIP
VOLTAGES

ON

OFF

ICL8212 OUTPUT STATE

OFF

ON

ICL8211 OUTPUT STATE

V

TR1

SUPPLY VOLTAGE

B

A

V

NOM

FIGURE 29B.

FIGURE 29. NON-VOLATILE LOW VOLTAGE INDICATOR

7-171

ON

OFF

ICL8212 OUTPUT STATE

V

TR2

ICL8211, ICL8212

have dropped to zero. Upon power up to the normal
operating voltage this record must have been retained and
easily interrogated. This could be important in the case of a
transient power failure due to a faulty component or
intermittent power supply, open circuit, etc., where direct
observation of the failure is difficult.

A simple circuit to record an out of range voltage excursion
may be constructed using an ICL8211, an ICL8212 plus a
few resistors. This circuit will operate to 30V without exceed­ing the maximum ratings of the ICs. The two voltage limits
defining the in range supply voltage may be set to any value
between 2.0V and 30V.

The ICL8212 is used to detect a voltage, V

, which is the

2

upper voltage limit to the operating voltage range. The
ICL8211 detects the lower voltage limit of the operating
voltage range, V

. Hysteresis is used with the ICL8211 so

1

that the output can be stable in either state over the
operating voltage range V
trip point of the ICL8211 much higher in voltage than V

to V2 by making V3 - the upper

1

.

2

The output of the ICL8212 is used to force the output of the
ICL8211 into the ON state above V

. Thus there is no value

2

of the supply voltage that will result in the output of the
ICL8211 changing from the ON state to the OFF state. This
may be achieved only by shorting out R3 for values of supply
voltage between V

and V2.

1

Constant Current Sources (Figure 32)

The ICL8212 may be used as a constant current source of
value of approximately 25µA by connecting the THRESH­OLD terminal to GROUND. Similarly the ICL8211 will pro­vide a 130µA constant current source. The equivalent
parallel resistance is in the tens of megohms over the supply
voltage range of 2V to 30V. These constant current sources
may be used to provide basing for various circuitry including
differential amplifiers and comparators. See Typical Operat­ing Characteristics for complete information.

Programmable Zener Voltage Reference (Figure 33)

The ICL8212 may be used to simulate a zener diode by
connecting the OUTPUT terminal to the V

output and using

Z

a resistor network connected to the THRESHOLD terminal
to program the zener voltage

=

(R1 + R2)

R

1

x 1.l5V.

V+

V

ZENER

R

R

4

R

5

1

ICL8212

2
3
4

8
7
6
5

3

FIGURE 30. NON-VOLATILE POWER SUPPLY MALFUNCTION RECORDER

OUTPUT ICL8211

ICL8212 DISCONNECTED OUTPUT ICL8212

V

NOM

OFF

OFF

RESET

R

2

R

V

S

1

1

NOM

1

ICL8211

2
3
4

8
7
6
5

R

6

OUTPUT

OUTPUT ICL8211

AS PER FIGURE 7

OFF

ON

V

1

SUPPLY VOLTAGE

ON

V

V

3

2

SUPPLY VOLTAGE

V

2

ON

V

1

SUPPLY VOLTAGE

FIGURE 31. OUTPUT STATES OF THE ICL8211 AND ICL8212 AS A FUNCTION OF THE SUPPLY VOLTAGE

7-172

V

2

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 typ­ical impedance values between 300µA and 25µA will range
from 4Ω to 7Ω. The knee is sharper and occurs at a signifi­cantly lower current than other similar devices available.

V+

1

=

1
2
3
4

I

8
7
6
5

I = 25µA (ICL8212)
I = 130µA (ICL8211)

OR

2
3
4

8
7
6
5

I

FIGURE 32. CONSTANT CURRENT SOURCE APPLICATIONS

6

5

V+

4

3

2

ZENER VOLTAGE

1

0

0.01 0.1 1.0 10 100
SUPPLY CURRENT (mA)

ICL

8212

V

OUT

V+

TH

I

S

500K

150K

R

2

+

R

5µF

–

1

ZENER

V

FIGURE 33. PROGRAMMABLE ZENER VOLTAGE REFERENCE

Precision Voltage Regulator (Figure 34)

The ICL8212 may be used as the controller for a highly sta­ble series voltage regulator. The output voltage is simply pro­grammed, using a resistor divider network R
capacitors C

and C2 are required to ensure stability since

1

and R2. Two

1

the ICL8212 is uncompensated internally.

Q

V+

UNREG­ULATED
DC SUPPLY

1

ICL8212

2
3
4

OUT

=

R2 + R

V

R

8
7
6
5

1

x 1.15V

R

1

FIGURE 34. PRECISION VOLTAGE REGULATOR

1

3

R

2

R

1

C

1

V+

C

2

This regulator may be used with lower input voltages than
most other commercially available regulators and also con­sumes 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.
Resistors R

and R2 set up the disconnect voltage and R

1

provides optional voltage hysteresis if so desired.

V+

R

V+

2

R

3

R

1

V-

R

2

R

3

R

1

V-

1
2
3
4

1
2
3
4

ICL8211

ICL8211

(a)

(b)

8
7
6
5

R

8
7
6
5

4

V+

CIRCUIT

BEING

PROTECTED

V-

V+

CIRCUIT

BEING

PROTECTED

V-

FIGURE 35. HIGH VOLTAGE DUMP CIRCUITS

Frequency Limit Detector (Figure 36)

Simple frequency limit detectors providing a GO/NO-GO out­put for use with varying amplitude input signals may be con­veniently implemented with the ICL8211/8212. In the
application shown, the first ICL8212 is used as a zero cross­ing detector. The output circuit consisting of R

, R4 and C

3

results in a slow output positive ramp. The negative range is
much faster than the positive range. R

and R6 provide hys-

5

teresis so that under all circumstances the second ICL8212
is turned on for sufficient time to discharge C
stant of R

Is much greater than R4 C2. Depending upon

7 C3

. The time con-

3

the desired output polarities for low and high input frequen­cies, 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.

3

2

7-173

ICL8211, ICL8212

SPST switches range from push button and slide types to cal­culator 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 millisec­ond 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 pro­vides a rapid charge up of C
voltage (V
charge of C
stant of R

) on a switch closure and a corresponding slow dis-

1

on a switch break. By proportioning the time con-

1

to approximately the manufacturer’s bounce time

1 C1

to close to the positive supply

1

the output as terminal #4 of the ICL8211/8212 will be a single
transition of state per desired switch closure

V+

INPUT

1
2

C

1

R

2

R

1

ICL8212 ICL8212

3
4

R

8

R

4

7

A

6
5

3

C

TIME CONSTANT R3C2 < R4C2≤ R7C
VARY R1 FOR OPTION ZERO CROSSING DETECTION
VARY R

R

6

R

5

2

TO SET DETECTION FREQUENCY

4

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 malfunc­tions 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.”

1
2
3
4

8

R

7

7

B

6
5

3

1

ICL8211

OR

2

ICL8212

3
4

C

3

#3

8
7

R

6

6
5

OUTPUT

INPUT

R

2

R

3

1.15V
A

1.15V
B

INDETERMINATE

ON TIME #2

BELOW F

OFF

ICL8211

OUTPUT STATE

ON

F

O

O

FREQUENCY

ON

OFF

ICL8212

OUTPUT STATE

FIGURE 36. FREQUENCY LIMIT DETECTOR

V+

R

100Ω

4

R

C

1

1

1

ICL8211

2

OR

3

ICL8212

4

8
7

R

6
5

L

500k

56k

V

O

1
2
3
4

ICL8212

4.7k

8
7
6

3.9k

5

V-

OUTPUT

REFERENCE

LM199

FIGURE 37. SWITCH BOUNCE FILTER FIGURE 38. LOW VOLTAGE POWER SUPPLY DISCONNECT

7-174