AIC431/TL431A/TL431
Adjustable Precision Shunt Regulator
Analog Integrations Corporation 4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan DS-431-07 012102
TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1
n FEATURES
l Precision Reference Voltage.
AIC431 :2.495V ±0.5%
TL431A :2.495V ±1.0%
TL431 :2.495V ±1.6%
l Sink Current Capability: 200mA.
l Minimum Cathode Current for Regulation: 250µA.
l Equivalent Full-Range Temperature Coefficient:
50 ppm/°C.
l Fast Turn-On Response.
l Low Dynamic Output Impedance: 0.08Ω.
l Adjustable Output Voltage.
l Low Output Noise.
l Space Saving Packages: SOT-89, SOT-23, TO-
92 and SO-8.
n APPLICATIONS
l Linear Regulators.
l Adjustable Supplies.
l Switching Power Supplies.
l Battery Operated Computers.
l Instrumentation.
l Computer Disk Drivers.
n TYPICAL APPLICATION CIRCUIT
VIN
AIC431
+
VOUT
R1
R2
+C2C1
R3
VOUT=(1+R1/R2)VREF
Precision Regulator
n DESCRIPTION
The AIC431, TL431A and TL431 are 3-
terminal adjustable precision shunt regulators
with guaranteed temperature stability over the
applicable extended commercial temperature
range. The output voltage may be set at any
level greater than 2.495V (VREF) up to 30V
merely by selecting two external resistors
that act as a voltage divider network. These
devices have a typical output impedance of
0.08Ω. Active output circuitry provides a very
sharp turn-on characteristics, making these
devices excellent improved replacements for
zener diodes in many applications.
The precise ±0.5% reference voltage toler-
ance of the AIC431 makes it possible in
many applications to avoid the use of a vari-
able resistor, consequently saving cost and
eliminating drift and reliability problems asso-
ciated with it.
AIC431/TL431A/TL431
2
n ORDERING INFORMATION
PIN CONFIGURATION
SOT-89 (CX)
FRONT VIEW
1: VREF
2: ANODE
3: CATHODE
1
2
3
1 2 3
TO-92 (CZ)
FRONT VIEW
1: VREF
2: ANODE
3: CATHODE
ANODE
REF
ANODE
NC
ANODE
ANODE
NC
CATHODE1
3
4
2
8
6
5
7
SO-8
TOP VIEW
SOT-23 (CUN)
FRONT VIEW
1: CATHODE
2: VREF
3: ANODE
SOT-23 (CUS)
FRONT VIEW
1: VREF
2: CATHODE
3: ANODE 12
3
3
12
PACKING TYPE
TR: TAPE & REEL
TB: TUBE (for SO-8)
BG: BAG
PACKAGE TYPE
S: SMALL OUTLINE
US: SOT-23
UN: SOT-23
X: SOT-89
Z: TO-92
AIC431 CXXX
TL431A CXXX
TL431
CX
XX
Example: AIC431CSTR
à in SO-8 Package & Taping &
Reel Packing Type
(CS is not available in BAG
packing type.)
n ABSOLUTE MAXIMUM RATINGS
Cathode Voltage ........……………...............……………..………...............................30V
Continuous Cathode Current ...................………….……...................... -10mA ~ 250mA
Reference Input Current Range .......…………........……..........…………………… 10mA
Operating Temperature Range, TA.......………….........….........……………. -40°C ~ 85°C
Lead Temperature .......…………..................………………..………………………. 260°C
Storage Temperature .......…………..................……………..…………….. -65°C ~ 150°C
Power Dissipation (Notes 1, 2) SOT-89 Package .........…………...... 0.80W
TO-92 Package ….......…………....... 0.78W
Note 1:TJ, max = 150°C.
Note 2: Ratings apply to ambient temperature at 25°C.
AIC431/TL431A/TL431
3
n TEST CIRCUITS
VREF
IREF IZ
VZ
IIN
IN
AIC431 R2
V
REF
I
REF
I
Z
V
Z
IN IIN
AIC431
Note: VZ=VREF(1+R1/R2)+IREFxR1
Fig. 1 Test Circuit for VZ=VREF Fig. 2 Test Circuit for VZ>VREF
IN
VZ
IZ(OFF)
AIC431
Fig. 3 Test Circuit for off-state Current
n ELECTRICAL CHARACTERISTICS (TA=25°C, unless otherwise specified.)
PARAMETER TEST CONDITIONS SYMBOL MIN. TYP. MAX. UNIT
VZ=VREF,AIC431 2.482 2.495 2.508
IIN =10mA (Fig. 1) TL431A 2.470 2.495 2.520
Reference Voltage
TL431
VREF
2.455 2.495 2.535
V
VZ = VREF , IIN =10mA,
TA = 0°C~ +70°C (Fig. 1) 9.0 20
Deviation of Reference
Input Voltage Over
Temperature (Note 3)
TA = -40°C~ +85°C (Fig. 1)
VDEV
9.0 50
mV
∆VZ=10V-VREF -0.5 -2.0 mV/V
Ratio of the Change in Refer-
ence Voltage to the Change
in Cathode voltage IZ=10mA
(Fig. 2) ∆VZ=30V-10V
∆VREF
∆VZ-0.35 -1.5 mV/V
AIC431/TL431A/TL431
4
n ELECTRICAL CHARACTERISTICS (Continued)
PARAMETER TEST CONDITIONS SYMBOL MIN. TYP. MAX. UNIT
Reference Input Current R1 =10KΩ, R2=∞,
IIN =10mA (Fig. 2) IREF 0.8 3.5 µA
Deviation of Reference Input
Current over Temperature R1 =10KΩ, R2=∞,
IIN =10mA
TA =-40°C ~ +85°C (Fig. 2) αIREF 0.31.2 µA
Minimum Cathode current for
Regulation VZ=VREF (Fig. 1) IZ(MIN) 0.25 0.5 mA
Off-State Current VZ=20V, VREF =0V (Fig. 3) IZ(OFF) 0.1 1.0 µA
Dynamic Output Impedance
(Note 4) VZ=VREF
F<1KHz (Fig. 1) RZ0.08 0.3 Ω
T2
T1
VMAX
VDEV = VMAX-VMIN
VMIN
TEMPERATURE
Note 3. Deviation of reference input voltage, VDEV, is de-
fined as the maximum variation of the reference input
voltage over the full temperature range.
The average temperature coefficient of the reference in-
put voltage, αVREF is defined as:
T1T2
10
C)25 (atVV
T1T2
6
10
C)25 (atVV-V
C
ppm
V
6
REF
DEV
REF
MINMAX
REF −
°
±
=
−
°
±
=
°
∆
Where:
T2−T1=full temperature change.
αVREF can be positive or negative depending on
whether the slope is positive or negative.
Example: VDEV= 9.0mV, VREF= 2495mV,
T2−T1= 70°C, slope is negative.
C50ppm/VC70
6
10
2495mV
9.0mV
REF °−=
=°
α
Note 4. The dynamic output impedance, Rz, is de-
fined as:
RZ = Z
ZV
I∆
∆
When the device is programmed with two external re-
sistors, R1 and R2, (see Fig. 2), the dynamic output
impedance of the overall circuit, is defined as:
[
]
R2
R1
1Rz
I
V
zr+≅
∆
∆
=
AIC431/TL431A/TL431
5
n TYPICAL PERFORMANCE CHARACTERISTICS
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
-600
-400
-200
0
200
400
600
800
1000
IZ(MIN)
VZ =VREF
TA =25°C
Fig. 4 Cathode Current vs. Cathode Voltage
Cathode Current (µA)
Cathode Voltage (V) -40 -20 0 20 40 60 80 100 120
2.40
2.42
2.44
2.46
2.48
2.50
2.52
2.54
2.56
2.58
Fig. 5
Reference Voltage vs. Temperature
VZ =VREF
IZ =10mA
Reference
Voltage (V)
Temperature (
°
C)
VREF=2.535V
VREF=2.495V
VREF=2.455V
-40 -20 0 20 40 60 80 100 120
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
Fig. 6
Reference Input Current vs. Temperature
Reference
Input
Current (
µ
A)
Temperature (
°
C)
R1=10KΩ
R2=∞
IZ=10mA
-40 -20 0 20 40 60 80 100 120
0.00
0.04
0.08
0.12
0.16
0.20
0.24
0.28
VZ=VREF
IZ=1mA to100mA
F <1KHz
Fig. 7 Dynamic Impedance vs. Temperature
Dynamic
Impedance (
Ω
)
Temperature (
°
C)
0
5
10
15
20
25
30
35
40
-6
-5
-4
-3
-2
-1
0
Fig. 8
Change in Reference Voltage vs. Cathode Voltage
Change
in
Reference
Voltage (mV)
Cathode
Voltage (V)
IZ =10mA
T
A
=25
°
C
-40
-20
0
20
40
60
80
100
120
0.0
0.5
1.0
1.5
2.0
2.5
Fig. 9 Off-State Cathode Current vs. Temperature
Off-State Cathode Current (µA)
Temperature (°C)
VREF=0V
VZ=30V
AIC431/TL431A/TL431
6
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
10
100
1k
10k
100k
10M
-10
0
10
20
30
40
50
60
70
80
IZ =10mA
TA=25°C
Fig. 10
Small Signal Voltage Amplification vs. Frequency
Small Signal Voltage Amplification (dB)
Frequency (Hz)
R1
10K R2
250
+
V
IN
CIN
47
µ
F
V1
AIC431
Output
Fig. 11
Test Circuit For
Frequency Response
Fig. 12 Pulse Response
Input
Output
RA
50
RB
220
AIC431
OUTPUT
Pulse
Generator
f=100kHz
Fig. 13 Test Circuit For Pulse Response
1E-4 1E-3 0.01 0.1 1 10
0
20
40
60
80
100
Fig. 14 Stability Boundary Conditions
Cathode Current (mA)
Load Capacitance (µF)
VZ=VREF Stable
Stable
CL
VIN
R
150
AIC431
VZ
Fig. 15 Test Circuit for Stability Boundary
The areas between the curves represent condition that
may cause the device oscillate
AIC431/TL431A/TL431
7
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
1K10K100K1M
0.1
1
10
Iz=10mA
TA=25°C
Fig. 16 Dynamic impedance vs. Frequency
Dynamic
Impedance (
Ω
)
Frequency (Hz)
R1
50
+
AC 3V
R2
50
AIC431
GND
Output
+
Fig. 17 Test Circuit for Dynamic Impedance
-
n SYMBOL n BLOCK DIAGRAM
ANODE (A)
REF (R)
CATHODE (C)
AIC431
ANODE (A)
CATHODE (C)
REF (R)
+
-
2.495V
n PIN DESCRIPTIONS
CATHODE Pin -Sinks current with a range from 250µA to 200mA for normal applications.
VREF Pin -Providing VREF=2.495V (typ.) for adjustable output voltage.
ANODE Pin -Anode pin sources current for normal application. The current value is the same as
Cathode pin.
AIC431/TL431A/TL431
8
n APPLICATION EXAMPLES
VIN
R1A
R2A
R1B
R2B AIC431
AIC431
R
3
R4
R
1
ON
OFF C
VIN
+AIC431
R
3
R
2
LED Turn on when Low Limit<VIN< High Limit
Low Limit ≅ VREF (1+R1B/R2B) Delay=R x C xln ( V
V V
IN
IN REF−)
High Limit ≅ VREF (1+R1A/R2A)
Fig. 18 Voltage Monitor Fig. 19 Delay Timer
RCL IOUT
VIN
AIC431
R1 R
VIN
S
IOUT
AIC431
R1
IOUT=VREF/ RCL IOUT=VREF /RS
Fig. 20 Current Limiter or Current Source Fig. 21 Constant-Current Sink
VOUT
R1
R2
VIN
AIC431
RIN R3 VIN
R2
VOUT
FUSE
AIC431
R3
R1
VOUT ≅ (1+R1/R2) x VREF VLIMIT ≅ (1+R1/R2) x VREF
Fig 22. Higher-Current Shunt Regulator Fig 23 Crow Bar
AIC431/TL431A/TL431
9
n APPLICATION EXAMPLES (Continued)
R1A
R2A
R2B
R1B
VIN
Output turn ON when
Low Limit <V
IN
< High Limit
+
VBE
AIC431
AIC431
R3
R4 R5
C1
Low Limit≅ VREF ( 1+ R1B/ R2B )+ VBE
High Limit ≅ VREF ( 1+ R1A/ R2A )
Fig 24. Over-Voltage/Under-Voltage Protection Circuit
n PHYSICAL DIMENSIONS
l 8 LEAD PLASTIC SO (unit: mm)
SYMBOL MIN MAX
A1.35 1.75
A1 0.10 0.25
B0.33 0.51
C0.19 0.25
D4.80 5.00
E3.80 4.00
e1.27(TYP)
H5.80 6.20
L0.40 1.27
D
H
e
A
B
A1
C
E
L
AIC431/TL431A/TL431
10
l SOT-23 (unit: mm)
SYMBOL MIN MAX
A1.00 1.30
A1 —0.10
A2 0.70 0.90
b0.35 0.50
C0.10 0.25
D2.70 3.10
E1.40 1.80
e1.90 (TYP)
H2.60 3.00
L0.37 —
H
A1
A
A2
b
θ1
L
C
D
E
e
θ11°9°
l SOT-23 MARKING
Part No. Marking Part No. Marking
AIC431CUN AC1N AIC431CUS AC1S
TL431CUN AC2N TL431CUS AC2S
TL431ACUN AC3N TL431ACUS AC3S
l SOT-89 (unit: mm)
SYMBOL MIN MAX
A1.40 1.60
B0.36 0.48
C0.35 0.44
D4.40 4.60
D1 1.62 1.83
E2.29 2.60
e1.50 (TYP.)
e1 3.00 (TYP.)
H3.94 4.25
B
e
H
e1
D
D1
A
C
L
E
L0.89 1.20
l SOT-89 MARKING
Part No. Marking
AIC431CX AC01B
TL431CX AC02B
TL431ACX AC03B
AIC431/TL431A/TL431
11
l TO-92 (unit: mm)
SYMBOL MIN MAX
A4.32 5.33
C0.38 (TYP.)
D4.40 5.20
E3.17 4.20
e1 1.27 (TYP.)
AL
e1
D
C
E
L12.7 -