HARRIS ICL8211CTY

ICL8211, ICL8212
S E M I C O N D U C T O R
Programmable Voltage Detectors
April 1994
Features
Description
• High Accuracy Voltage Sensing and Generation
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.
• 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
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.
Applications
Ordering Information
• Low Voltage Sensor/Indicator
• High Voltage Sensor/Indicator
PART NUMBER
TEMPERATURE
RANGE
PACKAGE
• Nonvolatile Out-of-Voltage Range Sensor/Indicator
ICL8211CPA
0oC to +70oC
8 Lead Plastic DIP
• Programmable Voltage Reference or Zener Diode
ICL8211CBA
0oC to +70oC
8 Lead SOlC (N)
• Series or Shunt Power Supply Regulator
ICL8211CTY
0oC to +70oC
8 Pin Metal Can
ICL8211MTY
(Note 1)
• Fixed Value Constant Current Source
-55oC
to
+125oC
8 Pin Metal Can
ICL8212CPA
0oC to +70oC
8 Lead Plastic DIP
ICL8212CBA
0oC to +70oC
8 Lead SOlC (N)
ICL8212CTY
0oC
ICL8212MTY
(Note 1)
to
+70oC
8 Pin Metal Can
-55oC to +125oC
8 Pin Metal Can
NOTE:
1. Add /883B to part number if 883B processing is required
Pinouts
ICL8211 (PDIP, SOIC)
TOP VIEW
ICL8211 (CAN)
TOP VIEW
HYSTERESIS
NC
1
8
V+
HYSTERESIS
2
7
NC
THRESHOLD
3
6
NC
OUTPUT
4
5
GROUND
8
THRESHOLD
OUTPUT
1
7
2
NC
V+
6
5
3
NC
NC
4
GROUND
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright
© Harris Corporation 1992
7-161
File Number
3184.1
ICL8211, ICL8212
Functional Diagram
VOLTAGE REFERENCE
COMPARATOR
OUTPUT BUFFERS
8
V+
Q4
Q3
Q2
R5
4.5kΩ
Q18
Q17
Q16
2
R4
1MΩ
Q5
Q6
Q1
Q14 Q15
Q19
XXXX
VREF
1.15V
3
Q12
Q7
HYST
Q23
THRESHOLD
Q13
R3
360kΩ
R1
20MΩ
4
OUTPUT
Q8
Q9
Q10
Q11
Q20
R6
100kΩ
Q21
R2
30kΩ
5
GROUND
ICL8211 OPTION
XXXXXX
ICL8212 OPTION
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
Thermal Resistance
θJA
θJC
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
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
Electrical Specifications
Storage Temperature Range. . . . . . . . . . . . . . . . . . -65oC to +150oC
V+ = 5V, TA = +25oC Unless Otherwise Specified
ICL8211
PARAMETER
Supply Current
Threshold Trip Voltage
Threshold Voltage
Disparity Between
Output & Hysteresis
Output
Guaranteed Operating
Supply Voltage Range
Minimum Operating
Supply Voltage Range
Threshold Voltage Temperature Coefficient
Variation of Threshold
Voltage with Supply
Voltage
Threshold Input Current
Output Leakage Current
SYMBOL
I+
VTH
VTHP
VSUPPLY
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
VTH = 1.3V
10
22
40
50
110
250
µA
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
+25oC (Note 3)
2.0
-
30
2.0
-
30
V
0oC
2.0 < V+ < 30
IOUT = 4mA
VOUT = 2V
IOUT = 4mA
IHYST = 7mA
VOUT = 2V
VHYST = 3V
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
∆VTH/∆T
IOUT = 4mA, VOUT = 2V
-
± 200
-
-
± 200
-
ppm/oC
∆VTH/∆V+
∆V+ = 10% at V+ = 5V
-
1.0
-
-
1.0
-
mV
VTH = 1.15V
-
100
250
-
100
250
nA
VTH = 1.00V
-
5
-
-
5
-
nA
VTH = 0.9V
-
-
-
-
-
10
µA
VTH = 1.3V
-
-
10
-
-
-
µA
VTH = 0.9V
-
-
-
-
-
1
µA
VTH = 1.3V
-
-
1
-
-
-
µA
VTH = 0.9V
-
0.17
0.4
-
-
-
V
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
VSUPPLY
ITH
IOLK
to
+70oC
VOUT = 30V
VOUT = 5V
Output Saturation
Voltage
Max Available Output
Current
Hysteresis Leakage
Current
ICL8212
VSAT
IOH
ILHYS
IOUT = 4mA
(Notes 3 & 4)
VOUT = 5V
V+ = 10V,
VHYST = GND
(Note 3)
7-163
ICL8211, ICL8212
Electrical Specifications
V+ = 5V, TA = +25oC Unless Otherwise Specified (Continued)
ICL8211
PARAMETER
SYMBOL
Hysteresis Sat Voltage
VHYS(MAX)
Max Available
Hysteresis Current
IHYS (MAX)
Electrical Specifications
TEST CONDITIONS
IHYST = -7µA,
measured with
respect to V+
ICL8212
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
VTH = 1.3V
-
-0.1
-0.2
-
-0.1
-0.2
V
VTH = 1.3V
-15
-21
-
-15
-21
-
µA
ICL8211MTY/8212MTY
V+ = 5V, TA = -55oC to +125oC
ICL8211
PARAMETER
Supply Current
Threshold Trip Voltage
Guaranteed Operating
Supply Voltage Range
SYMBOL
I+
VTH
VSUPPLY
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
2.8 < V+ < 30
-
-
-
-
-
-
-
VT = 1.3V
-
-
100
-
350
350
µA
VT = 0.8V
-
-
350
-
100
100
µA
V+ = 2.8V
0.80
-
1.30
0.80
-
1.30
V
V+ = 30V
0.80
-
1.30
0.80
-
1.30
V
2.8
-
30
2.8
-
30
V
-
-
400
-
-
400
nA
VTH = 0.8V
-
-
-
-
-
20
µA
VTH = 1.3V
-
-
20
-
-
-
µA
VTH = 0.8V
-
-
0.5
-
-
-
V
VTH = 1.3V
-
-
-
-
-
0.5
V
VTH = 0.8
3
-
15
-
-
-
mA
VTH = 1.3V
-
-
-
9
-
-
mA
IOUT = 2mA
VOUT = 2V
(Note 5)
Threshold Input Current
ITH
VTH = 1.15V
Output Leakage Current
IOLK
VOUT = 30V
Output Saturation
Voltage
Max Available Output
Current
VSAT
IOH
ICL8212
IOUT = 3mA
(Notes 3 & 4)
VOUT = 5V
ILHYS
V+ = 10V
VHYST = GND
VTH = 0.8V
-
-
0.2
-
-
0.2
µA
Hysteresis Saturation
Voltage
VHYS(MAX)
IHYST = -7µA
measured with
respect to V+
VTH = 1.3V
-
-
0.3
-
-
0.3
V
Max Available
Hysteresis Current
IHYS (MAX)
10
-
-
10
-
-
µA
Hysteresis Leakage
Current
VTH = 1.3V
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 IOUT = 3mA.
7-164
ICL8211, ICL8212
Typical Performance Curves
(ICL8211 and ICL8212)
0
TA = +25oC
V+ = +10V
V+ = +5V
VTH = 1.2V
-5 VHYS = 4.5V
HYSTERESIS OUTPUT CURRENT (µA)
THRESHOLD INPUT CURRENT (nA)
10,000
1,000
ICL8211 OR ICL8212
100
(OR -0.5V WITH RESPECT
TO V+ SUPPLY)
-10
-20
-25
ICL8211 OR ICL8212
-30
10
0.0
1.1 1.15 1.2
2.0
3.0
6.0
8.0 10.0
-40
-20
THRESHOLD VOLTAGE (VTH)
(IRREGULAR SCALE)
+40
+60
+80
TEMPERATURE ( C)
FIGURE 2. HYSTERESIS OUTPUT SATURATION CURRENT AS
A FUNCTION OF TEMPERATURE
(ICL8211 ONLY)
150
150
VTH = 0.9V
100
TA = +25oC
V+ = +5V
OUTPUTS OPEN
CIRCUIT
125
SUPPLY CURRENT (µA)
125
SUPPLY CURRENT (µA)
+20
o
FIGURE 1. THRESHOLD INPUT CURRENT AS A FUNCTION OF
THRESHOLD VOLTAGE
Typical Performance Curves
0
TA = +25oC
OUTPUTS OPEN CIRCUIT
75
50
100
75
50
25
25
VTH = 1.3V
0
0.0
0
10
20
30
SUPPLY VOLTAGE
FIGURE 3. SUPPLY CURRENT AS A FUNCTION OF SUPPLY
VOLTAGE
10
OUTPUT CURRENT (mA)
VTH = 0.9V
100
75
50
VTH = 1.3V
8
HYSTERESIS
OUTPUT
6
25
2
0
0
-20
OUTPUT
4
-15
-25
8mV
-55
-25
+5
+35
+65
+95
+125
1.12
TEMPERATURE oC
1.13
1.14
1.15
1.16
1.17
HYSTERESIS OUTPUT CURRENT (µA)
0
TA = +25oC
V+ = +5V
-5
VO = 0.5V
VHYS = V+ - 0.25V
-10
12
125
4.0
FIGURE 4. SUPPLY CURRENT AS A FUNCTION OF THRESHOLD VOLTAGE
150
SUPPLY CURRENT (µA)
1.0
1.1
1.15
1.2
2.0
THRESHOLD VOLTAGE (VTH)
(IRREGULAR SCALE)
-30
1.18
THRESHOLD VOLTAGE
FIGURE 5. SUPPLY CURRENT AS A FUNCTION OF TEMPERATURE
7-165
FIGURE 6. OUTPUT SATURATION CURRENTS AS A FUNCTION OF THRESHOLD VOLTAGE
ICL8211, ICL8212
Typical Performance Curves
(ICL8211 ONLY)
(Continued)
1.18
IO = 4mA, VO = 1V
IHYS = -7µA, VHYS = (V+ -2) V
OUTPUT
1.17
THRESHOLD VOLTAGE
THRESHOLD VOLTAGE
1.15
1.14
HYSTERESIS OUTPUT
V+ = +5V
IO = 1mA, VOUT = +5V
IHYS = -7µA, VHST = 0V
1.13
-55
-25
+5
+35
+65
TEMPERATURE (oC)
+95
1.16
OUTPUT
1.15
HYSTERESIS OUTPUT
1.14
1.13
+125
1
FIGURE 7. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST
ON” AS A FUNCTION OF TEMPERATURE
2
3 4 5
10
20 30 4050
SUPPLY VOLTAGE
100
FIGURE 8. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST
ON” AS A FUNCTION OF SUPPLY VOLTAGE
8
12
TA = +25oC
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
V+ = +5V
7
6
V+ = +5V
VTH = 1.1V
VO = 1.0V
5
-55
9
VTH = 1.0V
6
VTH = 1.147V
3
VTH = 1.152V
0
-25
+5
+35
+65
+95
+125
0.1
1.0
10.0
OUTPUT VOLTAGE
TEMPERATURE (oC)
FIGURE 9. OUTPUT SATURATION CURRENT AS A FUNCTION
OF TEMPERATURE
FIGURE 10. OUTPUT CURRENT AS A FUNCTION OF OUTPUT
VOLTAGE
HYSTERESIS OUTPUT CURRENT (µA)
0
-5
VT = 1.143V
-10
-15
VT = 1.144V
-20
-25
VT = 1.18V
-30
TA = +25oC
V+ = +10V
-35
-40
-10.00
100.0
-1.00
-0.10
-0.01
HYSTERESIS OUTPUT VOLTAGE
FIGURE 11. HYSTERESIS OUTPUT CURRENT AS A FUNCTION OF HYSTERESIS OUTPUT VOLTAGE
7-166
ICL8211, ICL8212
Typical Performance Curves
(ICL8212 ONLY)
150
150
TA = +25oC
OUTPUTS OPEN CIRCUIT
125
SUPPLY CURRENT - I+ (µA)
SUPPLY CURRENT (µA)
125
VTH = 1.3V
100
TA = +25oC
V+ = +5V
OUTPUTS OPEN CIRCUIT
75
50
100
75
50
25
25
VTH = 0.9V
0
0.0
0
10
20
1.0
30
1.15
1.2
2.0
FIGURE 12. SUPPLY CURRENT AS A FUNCTION OF SUPPLY
VOLTAGE
FIGURE 13. SUPPLY CURRENT AS A FUNCTION OF THRESHOLD VOLTAGE
150
0
30
V+ = 5V
OUTPUTS
OPEN
CIRCUIT
VTH = 1.3V
100
75
50
-5
25
OUTPUT CURRENT (mA)
125
4.0
THRESHOLD VOLTAGE (VTH)
(IRREGULAR SCALE)
SUPPLY VOLTAGE
SUPPLY CURRENT - I+ (µA)
1.1
VTH = 0.9V
25
+25oC
TA =
V+ = 5V
VOUT = 4V
VHYS = V+ -0.25V
20
15
-10
-15
HYSTERESIS OUTPUT
10
-20
5
-25
OUTPUT
0
1.14
0
-55
-25
+5
+35
+65
+95
+125
1.15
TEMPERATURE (oC)
1.16
1.17
1.18
1.19
HYSTERESIS OUTPUT CURRENT (µA)
0
-30
1.20
THRESHOLD VOLTAGE
FIGURE 14. SUPPLY CURRENT AS A FUNCTION OF TEMPERATURE
FIGURE 15. OUTPUT SATURATION CURRENTS AS A FUNCTION OF THRESHOLD VOLTAGE
1.18
1.17
IO = 1mA, VOUT = 5V
IHYS = -7µA, VHYS = 0V
THRESHOLD VOLTAGE
THRESHOLD VOLTAGE
1.17
1.16
BOTH OUTPUT AND
HYSTERESIS OUTPUT
1.15
1.16
BOTH OUTPUT AND
HYSTERESIS OUTPUT
1.15
TA = +25oC
IOUT = 4mA, VOUT = 1V
IHYS = -7µA, VHYS = (V+ -2) V
1.14
1.14
-55
1.13
-25
+5
+35
+65
+95
1
+125
2
3 4 5
10
20 30 4050
100
SUPPLY VOLTAGE
TEMPERATURE (oC)
FIGURE 16. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST
ON” AS A FUNCTION OF TEMPERATURE
FIGURE 17. THRESHOLD VOLTAGE TO TURN OUTPUTS “JUST
ON” AS A FUNCTION OF SUPPLY VOLTAGE
7-167
ICL8211, ICL8212
Typical Performance Curves
Detailed Description
(ICL8212 ONLY) (Continued)
The ICL8211 and ICL8212 use standard linear bipolar
integrated circuit technology with high value thin film
resistors which define extremely low value currents.
OUTPUT SATURATION VOLTAGE
0.6
OUTPUT SAT.
CURRENT
(VO = 4.0V)
0.5
Components Q1 through Q10 and R1, R2 and R3 set up an
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 oC).
0.4
VOLTAGE SAT.
CURRENT
(IO = 10mA)
0.3
0.2
0.1
Components Q2 through Q9 and R2 make up a constant
current source; Q2 and Q3 are identical and form a current
mirror. Q8 has 7 times the emitter area of Q9, and due to the
current mirror, the collector currents of Q8 and Q9 are forced
to be equal and it can be shown that the collector current in
Q8 and Q9 is
V+ = +5V
VTH = 1.2V
0
-55
-25
+5
+35
+65
+95
+125
TEMPERATURE (oC)
IC (Q8 or Q9) =
FIGURE 18. OUTPUT SATURATION VOLTAGE AND CURRENT
AS A FUNCTION OF TEMPERATURE
x
kT
q
In7
or approximately 1µA at +25oC
40
TA = +25oC
V+ = +5V
30
Where k = Boltzman’s Constant
q = Charge on an Electron
and T = Absolute Temperature in oK
20
Transistors Q5, Q6, and Q7 assure that the VCE of Q3, Q4,
and Q9 remain constant with supply voltage variations. This
ensures a constant current supply free from variations.
VTH =1.25V
OUTPUT CURRENT (mA)
1
R2
The base current of Q1 provides sufficient start up current for
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.
VTH = 1.158V
10
VTH = 1.153V
0
0.1
1.0
10.0
OUTPUT VOLTAGE
30.0 100.0
FIGURE 19. OUTPUT CURRENT AS A FUNCTION OF OUTPUT
VOLTAGE
Q4 is matched to Q3 and Q2; Q10 is matched to Q9. Thus the
IC and VBE of Q10 are identical to that of Q9 or Q8. To
generate the bandgap voltage, it is necessary to sum a
voltage equal to the base emitter voltage of Q9 to a voltage
proportional to the difference of the base emitter voltages of
two transistors Q8 and Q9 operating at two current densities.
HYSTERESIS OUTPUT CURRENT (µA)
0
-5
Thus 1.5 = VBE (Q9 or Q10) +
VT = 1.152V
R3
R2
x
kT
q
-10
VT = 1.153V
which provides:
-15
-20
-25
-40
-10.00
R2
= 12 (approximately.)
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 Q11 through Q17.
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 Q19 to 100µA.
VT = 1.18V
-30
-35
R3
TA = +25oC
V+ = +10V
-1.00
-0.10
-0.01
HYSTERESIS OUTPUT VOLTAGE
FIGURE 20. HYSTERESIS OUTPUT CURRENT AS A FUNCTION
OF HYSTERESIS OUTPUT VOLTAGE
In the case of the ICL8211, Q21 is proportioned to have 70
times the emitter area of Q20 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 Q21, resulting in a maximum available collector
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.
INPUT VOLTAGE
(RECOMMENDED
RANGE -5 TO +5V)
VTH
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 VTH. For high accuracy, 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
8
2
7
3
6
4
5
V+
(V+ MUST BE
EQUAL OR
EXCEED 1.8V)
RL1
1
8
2
7
3
6
4
5
VTH
VO
PULLUP RESISTOR
CMOS OR
TTL GATES
VHYST
RL2
VO2
FIGURE 22. OUTPUT LOGIC INTERFACE
VO1
V+
INPUT
R2
1.15V
0
VTH
R1
V+
0V
ICL8211 OUTPUT
1
8
2
7
3
6
4
5
V-
V+
0V
ICL8212 OUTPUT
FIGURE 21. VOLTAGE LEVEL DETECTION
FIGURE 23. INPUT RESISTOR NETWORK CONSIDERATIONS
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.
Case 1. High accuracy required, current in resistor network
unimportant Set I = 50µA for VTH = 1.15V ∴ R1 →
20kΩ
The regular OUTPUT’s from either the ICL8211 or ICL8212
may be used to drive most of the common logic families such
Case 2. Good accuracy required, current in resistor network
important Set I = 7.5µA for VTH = 1.15V ∴ R1 →
150kΩ
7-169
ICL8211, ICL8212
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.
V+
INPUT
R2
INPUT
VOLTAGE
R1
1
8
2
7
3
6
4
5
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.
V-
Input voltage to change to output states
(R1 + R2)
=
x 1.15V
R1
FIGURE 24. RANGE OF INPUT VOLTAGE GREATER THAN
+1.15 VOLTS
There are two simple methods to apply hysteresis to a circuit
for use in supply voltage level detection. These are shown in
Figure 27.
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.
MAY BE ANY STABLE VOLTAGE
VOLTAGE REFERENCE
GREATER THAN 1.15V
VREF (+VE)
R2
R1
1
8
2
7
3
6
4
5
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.
V+
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. R3 will provide hysteresis if required.
Range of input voltage less than +1.15V
Input voltage to change the output states
R2VREF
(R1 + R2) x 1.15
=
R1
R1
Nonvolatile Low Voltage Detector (Figure 29)
FIGURE 25. INPUT RESISTOR NETWORK SETUP
PROCEDURES
For supply voltage level detection applications the input
resistor network is connected across the supply terminals as
shown in Figure 26.
V+
R2
1
8
2
7
3
6
4
5
INPUT VOLTAGE
OR
SUPPLY VOLTAGE
R1
VO
FIGURE 26. COMBINED INPUT AND SUPPLY VOLTAGES
Case 2. Use of the HYSTERESIS function
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.
In this application the high trip voltage VTR2 is set to be
above the normal supply voltage range. On power up the
initial condition is A. On momentarily closing switch S1 the
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 VTR1 (even to zero
volts) and then raised back to VNOM.
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
7-170
ICL8211, ICL8212
V+
R3
R2
R2
1
8
2
7
3
6
4
5
R3
(NOTE 1)
1
8
ICL8211
2
7
3
6
4
5
LED
LAMP
150kΩ
R1
VO
NOTE 1. R3 OPTIONAL
Low trip voltage
VTR1 =
(R1 + R2) x 1.15 + 0.1V
R1
FIGURE 28. LOW VOLTAGE BATTERY INDICATOR
volts
High trip voltage
VTR2 =
(R1 + R2 + R3)
R1
x 1.15V
FIGURE 27A.
V+
V+
RQ
RS
1
8
2
7
3
6
4 FIG 7
5
R3
R2
RP
1
x
RP
1
8
2
7
3
6
4
5
RL
R1
VO
Low trip voltage
RQRS
+ RP
VTR1 =
(RQ + RS)
S1
OUTPUT
FIGURE 29A.
x 1.15V
High trip voltage
VTR2 =
(RP + RQ)
RP
x 1.15V
ON
OFF
VTR1
B
OFF
ON
OFF
ON
A
VTR1
VTR2
VNOM
ICL8212 OUTPUT STATE
ON
ICL8211 OUTPUT STATE
OFF
ICL8212 OUTPUT STATE
ICL8211 OUTPUT STATE
FIGURE 27B.
VTR2
SUPPLY VOLTAGE
SUPPLY VOLTAGE
FIGURE 29B.
FIGURE 27C.
FIGURE 27. TWO ATERNATIVE VOLTAGE DETECTION
CIRCUITS EMPLOYING HYSTERESIS TO
PROVIDE PAIRS OF WELL DEFINED TRIP
VOLTAGES
FIGURE 29. NON-VOLATILE LOW VOLTAGE INDICATOR
7-171
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, V2, which is the
upper voltage limit to the operating voltage range. The
ICL8211 detects the lower voltage limit of the operating
voltage range, V1. Hysteresis is used with the ICL8211 so
that the output can be stable in either state over the
operating voltage range V1 to V2 by making V3 - the upper
trip point of the ICL8211 much higher in voltage than V2.
The output of the ICL8212 is used to force the output of the
ICL8211 into the ON state above V2. Thus there is no value
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 V1 and V2.
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 VZ output and using
a resistor network connected to the THRESHOLD terminal
to program the zener voltage
VZENER =
(R1 + R2)
R1
x 1.l5V.
V+
R3
1
R4
8
ICL8212
2
S1
RESET
1
8
ICL8211
7
2
3
6
3
6
4
5
4
5
R2
7
R6
R5
OUTPUT
R1
FIGURE 30. NON-VOLATILE POWER SUPPLY MALFUNCTION RECORDER
OUTPUT ICL8211
ICL8212 DISCONNECTED
OUTPUT ICL8211
AS PER FIGURE 7
OUTPUT ICL8212
VNOM
VNOM
OFF
OFF
OFF
ON
ON
ON
V1
SUPPLY VOLTAGE
V2
V2
V3
SUPPLY VOLTAGE
V1
V2
SUPPLY VOLTAGE
FIGURE 31. OUTPUT STATES OF THE ICL8211 AND ICL8212 AS A FUNCTION OF THE SUPPLY VOLTAGE
7-172
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
8
2
7
8
3
6
2
7
4
5
3
6
4
5
=
OR
I
1
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 R1 and R2 set up the disconnect voltage and R3
provides optional voltage hysteresis if so desired.
I
V+
I = 25µA (ICL8212)
I = 130µA (ICL8211)
R2
1
2
FIGURE 32. CONSTANT CURRENT SOURCE APPLICATIONS
R3
ICL8211
8
V+
7
CIRCUIT
BEING
PROTECTED
3
6
4
5
6
5
V-
V+
4
(a)
IS
V+
V+
3
ICL
8212
2
500K
R2
R2
VTH
150K R1
+
–
5µF
OUT
1
VZENER
ZENER VOLTAGE
V-
R1
1
2
R3
8
ICL8211
3
R4
7
V+
6
4
5
R1
CIRCUIT
BEING
PROTECTED
0
V0.01
0.1
1.0
SUPPLY CURRENT (mA)
10
100
V(b)
FIGURE 35. HIGH VOLTAGE DUMP CIRCUITS
FIGURE 33. PROGRAMMABLE ZENER VOLTAGE REFERENCE
Precision Voltage Regulator (Figure 34)
Frequency Limit Detector (Figure 36)
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 R1 and R2. Two
capacitors C1 and C2 are required to ensure stability since
the ICL8212 is uncompensated internally.
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 R3, R4 and C2
results in a slow output positive ramp. The negative range is
much faster than the positive range. R5 and R6 provide hysteresis so that under all circumstances the second ICL8212
is turned on for sufficient time to discharge C3. The time constant of R7 C3 Is much greater than R4 C2. Depending upon
the desired output polarities for low and high input frequencies, either an ICL8211 or an ICL8212 may be used as the
output driver.
R3
V+
1
UNREG2
ULATED
DC SUPPLY
3
8
ICL8212
Q1
V+
R2
7
C2
6
4
5
R1
C1
VOUT =
R2 + R1
x 1.15V
R1
FIGURE 34. PRECISION VOLTAGE REGULATOR
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.
7-173
ICL8211, ICL8212
Low Voltage Power Disconnect (Figure 38)
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 C1 to close to the positive supply
voltage (V1) on a switch closure and a corresponding slow discharge of C1 on a switch break. By proportioning the time constant of R1 C1 to approximately the manufacturer’s bounce time
the output as terminal #4 of the ICL8211/8212 will be a single
transition of state per desired switch closure
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.”
V+
1
2
C1
8
ICL8212
1
R4
R6
7
3
6
4
5
A
8
2
ICL8212
R5
1
R7
7
3
6
4
5
2
B
3
ICL8211
OR
ICL8212
#3
8
7
6
R6
INPUT
R2
R1
4
5
R3
C2
OUTPUT
C3
TIME CONSTANT R3C2 < R4C2 ≤ R7C3
VARY R1 FOR OPTION ZERO CROSSING DETECTION
VARY R4 TO SET DETECTION FREQUENCY
INDETERMINATE
BELOW FO
INPUT
1.15V
B
OUTPUT STATE
ICL8212
ON TIME #2
1.15V
A
ON
OUTPUT STATE
ICL8211
OFF
ON
OFF
FO
FREQUENCY
FIGURE 36. FREQUENCY LIMIT DETECTOR
V-
V+
R4
100Ω
R2
1
2
3
4
R3
R1
500k
8
ICL8211
OR
ICL8212
8
2
7
6
1
3
RL
4
5
4.7k
OUTPUT
REFERENCE
7
ICL8212
6
5
3.9k
LM199
56k
C1
VO
FIGURE 37. SWITCH BOUNCE FILTER
FIGURE 38. LOW VOLTAGE POWER SUPPLY DISCONNECT
7-174