CM431
L
OW
V
OLTAGE
A
DJUSTABLE
S
HUNT
R
EGULATOR
GENERAL DESCRIPTION
The CM431 is a three-terminal adjustable shunt voltage regulator
with specified thermal stability and pin-to-pin compatible with the
earlier 431 series. The output voltage can be adjusted to any
value between V
REF
and 36V by using two external resistors. The
CM431 offers low output impedance for improved load regulation
with a typical output impedance of 200mΩ. Because of the
active output circuitry, the CM431 can replace the zener diodes in
applications such as switching power supplies, OVP crowbar
circuits, references for A/D, D/A converters with improved turn-on
characteristics.
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Voltage Reference
Precision shunt regulator
High current shunt regulator
PWM down converter with reference
Voltage monitor
FEATURES
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Initial voltage reference accuracy of 1.0%.
Sink current capability from 1mA to 100mA
Typical output dynamic impedance less than 200mΩ;
Adjustable output voltage from V
REF
to 36V
Available in SOT-23, SOT-89, TO-92, & SOP-8
Low output noise
Typical equivalent full range temperature coefficient of
30ppm/ C
O
APPLICATIONS
PIN CONFIGURATION
TO-92
Front View
SOT-23-3
Top View
3
CATHODE
REF
ANODE
CM431XCM233
Pin 1
Pin 2
Pin 3
1
2
CM431XCM2R3
CATHODE
REF
ANODE
REF
CATHODE
ANODE
Suffix “X”: Grade “A”, “B”, “C”, or “D”
1
2
3
SOT-23-5
Top View
5
4
SOT-89
Top View
1
SOP-8
Top View
C OE
ATH D
N
C
N
C
N
C
R
EF
N
C
AN D
OE
N
C
8
7
6
5
CATHO D E REF
CATHODE
ANO DE
REF
ANODE
2
3
4
NC
NC
1
2
3
1
2
3
2003/03/24
Preliminary
Rev.1.1
Champion Microelectronic Corporation
Page 1
CM431
L
OW
V
OLTAGE
A
DJUSTABLE
S
HUNT
R
EGULATOR
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, these specifications apply over the operating ambient temperatures with T
A
= 25°C.
°
Parameter
Symbol
Test Conditions
I
K
= 10mA, V
KA
= V
REF
,0.5%
CM431
Min
2.482
2.478
2.470
Typ
2.495
2.495
2.495
Max
2.507
2.512
2.520
Units
V
V
V
Reference Input Voltage
Reference Drift
V
REF
I
K
= 10mA, V
KA
= V
REF
,0.7%
I
K
= 10mA, V
KA
= V
REF
,1.0%
I
K
= 10mA, V
KA
= V
REF
, 0 C
≤
T
A
≤
70
O
2003/03/24
Preliminary
Rev.1.1
Champion Microelectronic Corporation
Page 4
CM431
L
OW
V
OLTAGE
A
DJUSTABLE
S
HUNT
R
EGULATOR
TYPICAL CHARACTERISTICS
Cathode Current vs. Cathode Voltage
Cathode Current vs. Cathode Voltage
Ref. Input Voltage vs. Free-Air Temperature
Ref. Input Current vs. Free-Air Temperature
2003/03/24
Preliminary
Rev.1.1
Champion Microelectronic Corporation
Page 6
CM431
L
OW
V
OLTAGE
A
DJUSTABLE
S
HUNT
R
EGULATOR
APPLICATION INFORMATION
V
BATT
R*
V
O
R1
0.1%
V
REF
R2
0.1%
Input
V
BATT
CM431
CM431
V
O
V
on
≈
2V
V
off
≈
V
BATT
V
th
= 2.5V
GND
V
O
= (1 + R1/R2)
×
V
REF
Note: R should provide 1mA cathode current to the
CM431 of minimum V
BATT
Figure 4. Shunt Regulator
Figure 5. Single –Supply Comparator With Temperature
compensated threshold.
V
BATT
V
O
V
BATT
R1
CM431
R2
C
V
O
R1
R2
CM431
V
O
= (1 + R1/R2)
×
V
REF
Figure 6. High-Current Shunt Regulator
Figure 7.
Crowbar Circuit
2003/03/24
Preliminary
Rev.1.1
Champion Microelectronic Corporation
Page 7
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