HTC LM431 Programmable precision shunt regulator Datasheet

PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
FEATURES
 Programmable Output Voltage to 40V
 Guaranteed 0.5% Reference Voltage Tolerance
 Low (0.2Ω Typ.) Dynamic Output Impedance
 Cathode Current Range(Continuous) – 100 ~ 150 mA
SOT-23 PKG
 Equivalent Full Range Temperature Coefficient of
50PPM/℃
 Temperature Compensated For Operation Over
Full Rate Operating Temperature Range
 Low Output Noise Voltage
 Fast Turn-on Response
 SOT-23 3L Package
APPLICATION
 Shunt Regulator
 Precision High-Current Series Regulator
 High-Current Shunt Regulator
 Crowbar Circuit
ORDERING INFORMATION
DEVICE
 PWM Converter With Reference
PACKAGE
LM431SF
 Voltage Monitor
SOT-23 3L
* Refer to the page 2 for detailed ordering Information,
 Precision Current Limiter
DESCRIPSION
The LM431 is a three-terminal adjustable shunt regulator with specified thermal stability over applicable
temperature VREF (Approx. 2.5V) and 40V with two external resistors. This device has a typical dynamic output
impedance of 0.2Ω. Active output circuitry provides a very sharp turn-on characteristic, making this device
excellent replacement for zener diodes in many applications. The LM431 is characterized for operation from 40℃ to +125℃.
ABSOLUTE MAXIMUM RATINGS
(Operating temperature range applies unless otherwise specified)
CHARACTERISTIC
SYMBOL
MIN.
MAX.
UNIT
VKA
-
42
V
IK
-100
150
mA
IREF
-0.05
10
mA
TJ
-40
150
℃
Operating Temperature Range
TOPR
-40
125
℃
Storage Temperature Range
TSTG
-60
150
℃
Cathode Voltage
Cathode Current Range(Continuous)
Reference Input Current Range
Junction Temperature Range
Apr. 2012 – Rev.1.1
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
RECOMMENDED OPERATING CONDITIONS
CHARACTERISTIC
SYMBOL
MIN.
MAX.
UNIT
Cathode Voltage
VKA
VREF
40
V
Cathode Current
IK
0.5
100
mA
Supplied As
Status
ORDERING INFORMATION
Package
Tolerance
Order No.
Package Marking
0.5%
LM431CSF
431O
Reel
Active
1%
LM431ASF
431O
Reel
Active
SOT-23
LM 431
Package Type
SF : SOT23 3L
C : 0.5%
A : 1%
Tolerance
Root Name
Product Code
PIN CONFIGURATION
PIN DESCRIPTION
2
Pin No.
Name
Function
1
Cathode
Input Supply Voltage
2
Anode
Ground
3
Reference
Reference Voltage
TOP
1
3
SOT-23 PKG
Apr. 2012 – Rev.1.1
SOT-23
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
LM431 ELECTRICAL CHARACTERISTICS
(TA=25℃, unless otherwise specified)
CHARACTERISTIC
Reference Voltage
Deviation of
Reference Voltage
Ratio of Change in
Reference Voltage to the
Change in Cathode Voltage
Reference Current
Deviation of Reference
Current
SYMBOL
VREF
ΔVREF/ΔT
ΔVREF/ΔVKA
TEST CONDITION
MIN.
TYP.
MAX.
0.5 %
2.487
2.500
2.512
1%
2.475
2.500
2.525
8
20
ΔVKA=10V -VREF
-1.4
-2.7
ΔVKA=36V-10V
-1.0
-2.0
UNIT
V
VKA =VREF, IK =10mA
VKA = VREF, IK =10mA
TA =Full Range
mV
mV/V
IK =10mA
IREF
IKA=10mA, R1=10㏀, R2=∞
1.8
4.0
uA
ΔIREF/ΔT
IK =10mA, R1=10㏀, R2=∞
TA =Full Range
0.4
1.2
uA
0.5
mA
Minimum Cathode Current
for Regulation
IK(MIN)
VKA= VREF
Off-State Cathode Current
IK(OFF)
VKA=36V, VREF=0
0.17
0.90
uA
VKA= VREF, IK =1mA~100mA
f ≤ 1kHz
0.27
0.50
Ω
Dynamic Impedance
ZKA
TEST CIRCUITS
[ Fig 1. Test circuit for VKA = VREF ]
Apr. 2012 – Rev.1.1
[ Fig 2. Test circuit for VKA ≥ VREF ]
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
[ Fig 3. Test circuit for IKA(OFF) ]
The deviation parameters ΔVREF/ΔT and ΔIREF/ΔT are defined as the differences between the maximum and
minimum values obtained over the recommended temperature range. The average full-range temperature
coefficient of the reference voltage, αVREF, is defined as :
Where :
ΔTA is the recommended operating free-air temperature range of the device.
αVREF can be positive or negative, depending on whether minimum VREF or maximum VREF, respectively, occurs at
the lower temperature.
Calculating Dynamic Impedance
The dynamic impedance is defined as :
Z KA 
VKA
I KA
When the device is operating with two external resistors, the total dynamic impedance of the circuit is given by :
Z' 
R1 
V

 Z KA 1 

R2 
I

Apr. 2012 – Rev.1.1
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
TYPICAL OPERATING CHARACTERISTICS
REFERENCE VOLTAGE vs
JUNCTION TEMPERATUR
2.504
PULSE RESPONSE
6
5
Input & Output Voltage (V)
VREF-Reference Voltage (V)
2.502
2.501
2.500
2.499
2.498
2.497
2.496
4
3
Output
2
1
2.495
0
0
20
40
60
80
100
120
-1
0
1
2
TJ-Junction Temperature (℃)
4
5
6
7
8
CATHODE CURRENT vs
CATHODE VOLTAGE
0.15
800
VKA=VREF
TA=25℃
0.13
3
t-Time (us)
CATHODE CURRENT vs
CATHODE VOLTAGE
VKA=VREF
TA=25℃
0.10
IKA-Cathode Current (uA)
IKA-Cathode Current (mA)
VKA=VREF
IKA=10mA
TA=25℃
Input
2.503
0.08
0.05
0.03
0.00
-0.03
-0.05
600
400
200
0
-0.08
-0.10
-200
-2.0
-1.0
0.0
1.0
2.0
-1.0
3.0
0.0
1.0
2.0
3.0
VKA-Cathode Voltage (V)
VKA-Cathode Voltage (V)
T.B.D
Apr. 2012 – Rev.1.1
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
APPICATION INFORMATION
1. Shunt Regulator
LM431
Note A : R Should provide cathode current 1mA to the LM431 at minimum VI(BATT)
2. Precision High-Current Series Regulator
LM431
Note A : R Should provide cathode current≥1mA to the LM431 at minimum VI(BATT)
3. Output Control of a Three-Terminal Fixed Regulator
LM431
Apr. 2012 – Rev.1.1
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
4. High-Current Shunt Regulator
LM431
5. Precision 5V 1.5A Regulator
LM431
6. Efficient 5-V Precision Regulator
LM431
NOTE A : RB Should provide cathode current≥1mA to the LM431.
Apr. 2012 – Rev.1.1
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
7. PWM Converter With Reference
LM431
8. Voltage Monitor
LM431
NOTE A : R3 and R4 are selected to provide the desired LED intensity and cathode current ≥1mA to the LM431 at the available VI(BATT).
9. Delay Timer
LM431
Apr. 2012 – Rev.1.1
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HTC
PROGRAMMABLE PRECISION SHUNT REGULATOR
LM431/A/C
10. Precision Current Limiter
LM431
11. Precision Constant-Current Sink
LM431
Apr. 2012 – Rev.1.1
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HTC
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