Precision Adjustable
Shunt Reference
CL431
FEATURES
Trimmed 0.5% Bandgap Reference
Nominal Temperature Range Extended to 105
o
C
Temperature-Compensated: 30ppm/
o
C
Internal Amplifier with 150mA Capability
Low Output Noise
Low Frequency Dynamic Output Impedance
DESCRIPTION
The CL431 is an adjustable shunt regulator designed to act as
an open-loop error amplifier with a 2.5V temperature
compensated reference. Its highly accurate 0.5% bandgap
reference is perfect for applications requiring stability and
accuracy over temperature and life.
Sharp turn-on characteristics and a low temperature
coefficient make the CL431 an excellent replacement for
many zener diode applications, programmable to any value
greater than 2.5V and up to 36V by using two external
resistors. As a combination error amplifier and reference, it
can be used to manage control loops such as switching power
supplies.
The CL431 can be used as a direct replacement for the
standard TL431.
ORDERING INFORMATION
Part
Package
Temperature Range
CL431LP
TO-92
0 to 105
o
C
CL431D
8-Pin Plastic SOIC
0 to 105
o
C
CL431S
SOT-89
0 to 105
o
C
CORPORATION
CALOGIC CORPORATION,
237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025
CATHODE
ANODE
REFERENCE
TO-92 (LP)
1G-33
SOIC (D)
8
7
6
5
1
2
3
4
REFERENCE
ANODE
ANODE
N/C
CATHODE
ANODE
ANODE
N/C
1G-34
1G-35
CATHODE
ANODE
REFERENCE
SOT-89 (S)
PIN CONFIGURATION (Top View)
CL431
ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
RATING
UNITS
V
KA
Cathode-Anode Reverse Breakdown
37
V
I
AK
Anode-Cathode Forward Current
1
A
I
KA
Operating Cathode Current
250
mA
I
REF
Reference Input Current
10
mA
P
D
Continuous Power at 25
o
C
TO-92
8L
SOIC
SOT-89
775
750
1000
mW
mW
mW
T
J
Junction Temperature
150
o
C
T
STG
Storage Temperature
65 to 150
o
C
T
L
Lead Temperature, Soldering 10 Seconds
300
o
C
Exceeding ABSOLUTE MAXIMUM RATINGS may cause permanent damage. Extended operation of the device at these or any other conditions
above those indicated in the operational sections of this specification is not recommended as it may adversely affect reliability and performance.
RECOMMENDED CONDITIONS
SYMBOL
PARAMETER
RATING
UNIT
V
KA
Cathode Voltage
V
REF
to 20
V
I
K
Cathode Current
10
mA
TYPICAL THERMAL RESISTANCE
PACKAGE
JA
JC
TYPICAL DERATING
TO-92
160
o
C/W
80
o
C/W
6.3mW/
o
C
SOIC
175
o
C/W
45
o
C/W
5.7mW/
o
C
SOT-89
110
o
C/W
8
o
C/W
9.1mW/
o
C
CALOGIC CORPORATION,
237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025
1G-36
ANODE (A)
CATHODE (K)
2.5V
REFERENCE (R)
+
FUNCTIONAL BLOCK DIAGRAM
CORPORATION
CL431
CALOGIC CORPORATION,
237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025
ELECTRICAL CHARACTERISTICS
Electrical Characteristics are guaranteed over full junction temperature range (0 to 105
o
C). Ambient temperature must be derated based on
power dissipation and package thermal characteristics. The conditions are: V
KA
= V
REF
and I
K
= 10mA unless otherwise stated.
SYMBOL
PARAMETER
CL431 (0.5%)
UNIT
TEST
CIRCUIT
TEST CONDITION
MIN
TYP
MAX
V
REF
Reference Voltage
2.490
2.503
2.515
V
1
T
A
= 25
o
C
2.469
2.536
V
1
Over Temp.
TC
V
REF
with Temp.*
0.07
0.20
mV/
o
C
1
V
REF
V
K
Ratio of Change in V
REF
to
Cathode Voltage
2.7
1.0
mV/V
2
V
REF
to 10V
2
0.4
0.3
10V to 36V
I
REF
Reference Input Current
0.7
4
A
2
I
REF
I
REF
Temp Deviation
0.4
1.2
A
2
Over Temp.
I
K(MIN)
Min I
K
for Regulation
0.4
1
mA
1
I
K(OFF)
Off State Leakage
0.04
250
nA
3
V
REF
= 0V, V
KA
= 36V
Z
KA
Dynamic Output Impedance
0.15
0.5
1
f
1kHz, I
K
= 1 to 150mA
0
15
30
45
60
75
90
105
TEMPERATURE (C)
0.07 mV/C
0.003 %/C
27 ppm/C
0.5
5000
0
0
0
mV
%
ppm
10
V
REF
T
1G-37
TC in
mV/
o
C
=
V
REF
(
mV
)
T
A
TC in
%/
o
C
=
V
REF
V
REF
at
25
o
C
x 100
T
A
TC in
ppm/
o
C
=
V
REF
V
REF
at 25
o
C
x 10
6
T
A
*CALCULATING AVERAGE TEMPERATURE COEFFICIENT (TC)
TEST CIRCUITS
IN
V
KA
V
K
I
1G-38
REF
I
REF
= V
REF
I
IN
V
KA
V
2
R
1
R
REF
(V
)
K
I
1G-39
IN
V
KA
V
K(OFF)
I
1G-40
TEST CIRCUIT 1
TEST CIRCUIT 2
TEST CIRCUIT 3
CORPORATION
CL431
TYPICAL PERFORMANCE CURVES
CALOGIC CORPORATION,
237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025
100
0.01
60
1G-43
OFF STATE LEAKAGE
30
0
30
60
90
120
10
1
0.1
CURRENT (nA)
V
KA
= 36V
V
REF
= 0V
AMBIENT TEMPERATURE (C)
T
A
OFF STATE CATHODE
I
Z
off
150
100
2
3
1G-42
HIGH CURRENT OPERATING
CHARACTERISTICS
75
50
25
0
25
50
75
125
100
2
1
0
1
CATHODE VOLTAGE (V)
V
KA
TEMPERATURE RANGE: 55 to 125C
V
KA
= V
REF
CATHODE CURRENT (m
A)
I
K
2.54
2.46
60
1G-44
TEMPERATURE COEFFICIENT AS
A FUNCTION OF TRIM VALUE
30
2.47
2.48
2.49
2.50
2.51
2.52
2.53
0
30
60
90
120
V
RE
F
RE
F
E
RE
NCE VOLTAGE (
V
)
AMBIENT TEMPERATURE
T
A
V
KA
= V
REF
I
K = 10mA
V
REF
= 2.503V AT 25C
V
KA
CATHODE VOLTAGE (V)
CATHODE CURRENT (
A)
I
K
900
200
1.0
3.0
1G-41
LOW CURRENT OPERATING
CHARACTERISTICS
1.0
0
2.0
100
800
700
600
500
400
300
200
100
0
125C
55C
25C
V
= V
REF
KA
TEMPERATURE RANGE: 55 to 125C
0
50
0
30
1G-46
REFERENCE VOLTAGE
LINE REGULATION
3
6
9
12 15 18 21 24 27
10
20
30
40
VOLTAGE (mV)
CHANGE IN REFERENCE
V
REF
CATHODE VOLTAGE (V)
V
KA
I
K
= 10mA
TEMPERATURE RANGE: 55 to 125C
55C
0C
25C
75C
125C
3.0
0
60
1G-45
REFERENCE
INPUT CURRENT
30
0
30
60
90
120
2.5
2.0
1.5
1.0
0.5
CURRENT (
A)
REFERENCE INPUT
I
REF
T
A
AMBIENT TEMPERATURE (C)
R1 = 10k
R2 =
I
K
= 10mA
CORPORATION
CL431
CORPORATION
CALOGIC CORPORATION,
237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025
TYPICAL PERFORMANCE CURVES (continued)
70
0
10
1G-47
NOISE VOLTAGE
100k
f FREQUENCY (Hz)
60
50
40
30
20
10
10k
1k
100
NOISE VOLTAGE nV/
Hz
V
KA
= V
REF
= 10mA
T
A
= 25C
I
K
0.150
0.0
60
1G-48
LOW FREQUENCY DYNAMIC
OUTPUT IMPEDANCE
30
0
30
60
90
120
0.125
0.100
0.075
0.050
0.025
DYNAMIC IMPEDANCE (
)
Z
KA
V
KA
= V
REF
= 1 TO 100mA
f
1kHz
I
KA
FREE AIR TEMPERATURE
T
A
100
0.01
1k
1G-49
DYNAMIC OUTPUT
IMPEDANCE
10M
f FREQUENCY (Hz)
1M
100k
10k
10
1.0
0.1
DYNAMIC IMPEDANCE (
)
Z
KA
T
A
= 25C
= 1 TO 100mA
I
K
70
0
1k
1G-50
SMALL SIGNAL GAIN
vs FREQUENCY
10M
f FREQUENCY (Hz)
60
50
40
30
20
10
1M
100k
10k
I
K = 10mA
G
A
IN
(dB)
SMALL SIG
N
AL V
O
LTAGE
A
V
T
A
= 25C
1H-01
K
I
230
GND
OUT
15k
8.25k
9
F
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