1
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2003 Sipex Corporation
Precision Adjustable Shunt Regulator
SPX2431
DESCRIPTION
FEATURES
Trimmed Bandgap to 0.5% and 1.0%
Wide Operating Current 1mA to 100mA
Extended Temp. Range: 0C to 105C
Low Temperature Coefficient 30 ppm/C
Offered in 3 Pin SOT-23 (M)
Replacement for TL431, AS2431
Low Noise Output
The SPX2431 is a 3-terminal adjustable shunt voltage regulator providing a highly accurate
bandgap reference. The SPX2431 acts as an open-loop error amplifier with a 2.5V temperature
compensation reference. The SPX2431's thermal stability, wide operating current (100mA) and
temperature range (0C to 105C) makes it suitable for a variety of applications that require a
low cost, high performance solution. SPX2431A tolerance of 0.5% is proven to be sufficient to
overcome all of the other errors in the system to virtually eliminate the need for trimming in the
power supply manufacturer's assembly line and contribute a significant cost savings.
The output voltage may be adjusted to any value between V
REF
and 20 volts with two external
resistors. In the standard shunt configuration, the combination of a low temperature coefficient,
sharp turn on characteristics, low output impedance, and programmable output voltage makes
this precision reference an excellent error amplifier. The SPX2431 is available in SOT-23-3
package.
APPLICATIONS
Battery Operating Equipment
Adjustable Supplies
Switching Power Supplies
Error Amplifiers
Single Supply Amplifier
Monitors / VCRs / TVs
Personal Computers
FUNCTIONAL DIAGRAM
+
-
2.5V
Reference
(R)
Anode (A)
Cathode (K)
2
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2004 Sipex Corporation
Cathode-Anode Reverse Breakdown V
KA
....................................... 20V
Anode-Cathode Forward Current, (<10ms) I
AK
................................. 1A
Operating Cathode Current I
KA
.................................................. 100mA
Reference Input Current I
REF
....................................................... 1.0mA
Continuos Power Dissipation at 25C P
D
SOT-23 .................................................................. 200 mW
Junction Temperature T
J
........................................................... 150 C
Storage Temperature T
STG
.............................................. -65 to 150 C
Lead Temperature (Soldering 10 sec.) T
L
.................................. 300C
NOTE: Stresses greater than those listed under ABSOLUTE MAXIMUM
RATINGS may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or any other
conditions above those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating condi-
tions for extended periods may affect reliability.
TYPICAL THERMAL RESISTANCES
PACKAGE
0
JA
0
JC
TYPICAL DERATING
SOT-23
575C/W 150C/W
1.7 mW/C
Typical deratings of the thermal resistances are given for ambient
temperature >25.
ELECTRICAL CHARACTERISTICS
Electrical characteristics at 25
C I
K
= 10mA V
K
= V
REF
, unless otherwise specified.
PARAMETER
SYMBOL
FIGURE
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
SPX2431A
SPX2431
Reference Voltage
V
REF
2
2.487
2.500
2.513
2.474
2.500
2.526
V
2
T
J
= 0C to 105C
2.480
2.520
2.460
2.540
V
V
REF
withTemp.*
TC
2
0.07
0.20
0.07
0.20
mV/C
Ratio of Change in V
REF
V
REF
V
REF
to 10V
-2.7
-1.01
-2.7
-1.01
mV/V
to Cathode Voltage
V
K
3
10V to 20V
-2.0
-0.4
0.3
-2.0
-0.4
0.3
Reference Input Current
I
REF
3
0.7
4.0
0.7
4.0
A
I
REF
Temp Deviation
I
REF
3
T
J
= 0C to 105C
0.4
1.2
0.4
1.2
A
Min I
K
for Regulation
I
K(MIN)
2
0.4
1.0
0.4
1.0
mA
Off State Leakage
I
K(OFF)
V
REF
= 0V,
0.04
0.04
500
nA
4
V
KA
= 20V
Dynamic Output
Z
KA
2
z
1kHz
0.15
0.5
0.15
0.5
Impedance
I
K
= 1 to 100mA
RECOMMENDED CONDITIONS
PARAMETER
SYMBOL
RATING
UNIT
Cathode Voltage
V
KA
V
REF
to 20
V
Cathode Current
I
K
10
mA
ABSOLUTE MAXIMUM RATINGS
3
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2003 Sipex Corporation
0
5000
ppm
0
0.5
%
27ppm/C
0.0027% / C
0.0033mV /C
0
15
30
45
60
75
90
105
0
mV
-5
T
V
REF
Junction Temperature (C)
V
REF
(mV)
T
A
(
V
REF
at 25C
)
T
A
V
REF
x 100
TC in % / C =
TC in mV / C =
(
V
REF
at 25C
)
T
A
V
REF
x 10
6
TC in ppm / C =
CALCULATING AVERAGE TEMPERATURE COEFFICIENT (TC)
Figure 1. V
REF
VS Temperature
TEST CIRCUITS
I
REF
V
KA =
V
REF
V
IN
I
K
I
REF
V
KA
V
IN
I
K
(V
REF
)
R1
R2
V
KA
V
IN
I
K (OFF)
Figure 2. Test Circuit for V
KA
= V
REF
Figure 3. Test Circuit for V
KA
> V
REF
Figure 4. Test Circuit for I
KOFF
4
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2004 Sipex Corporation
-2
-1
0
1
2
3
150
125
100
75
50
25
0
-25
-50
-75
-100
V
KA
Cathode Voltage (V)
I
K
Cathode Current (mA)
V
KA
= V
REF
0C to 105C
-60
-30
0
30
60
90
120
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
2.45
T
A
Ambient Temperature (C)
V
REF
Reference V
oltage (V)
V
KA
= V
REF
I
K
= 10mA
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 5. High Current Operating Characteristics
Figure 6. Reference Voltage VS Ambient Tempetature
-1.0
0
1.0
2.0
3.0
900
800
700
600
500
400
300
200
100
0
-100
-200
V
KA
Cathode Voltage (V)
I
K
Cathode Current (
A)
V
KA
= V
REF
0 to 105C
105C
25C
-0C
-60
-30
0
30
60
90
120
3.0
2.5
2.0
1.5
1.0
0.5
0
T
A
Ambient Temperature (C)
I
REF
Reference Input Current (
A)
R1 = 10k
R2 =
I
K
= 10mA
Figure 7. Low Current Operating Characteristics
10
100
1K
10K
100K
70
60
50
40
30
20
10
0
f Frequency (Hz)
Noise V
oltage n/
Hz
V
KA
= V
REF
I
K
= 10mA
T
A
= 25C
0
3
6
9
12 15
18
21
24
27 30
0
-10
-20
-30
-40
-50
V
KA
Cathode Voltage (V)
V
REF
(mV)
0C
25C
75C
125C
I
KA
= 10mA
Figure 9. Reference Voltage Line Regulation VS
Cathode Voltage and T
AMBIENT
Figure 10. Noise Voltage VS Frequency
Figure 8. Reference Input Current VS Ambient
Temperature
5
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2003 Sipex Corporation
V
IN
V
OUT
V
IN
V
OUT
TYPICAL PERFORMANCE CHARACTERISTICS: Continued
-60
-30
0
30
60
90
120
0.150
0.125
0.100
0.075
0.050
0.025
0.0
T
A
Free Air Temperature
Z
KA
Dynamic Impedance (
)
V
KA
= V
REF
I
K
= 1 to 100mA
f1kHz
Figure 11. Low Frequency Dynamic Output Impedance
VS T
AMBIENT
10
100
1K
10K
100K
1M
10M
START 10.000Hz
STOP 50 000 000.000Hz
REF LEVEL
60.000dB
0.0deg
/DIV
10.000dB
45.000deg
MARKER 25 297
MAG (A/R)
MARKER 25 297
PHASE (A/R)
698.000 Hz
-0.025 dB
698.000 Hz
93.320 deg
GAIN
PHASE
60dB
50dB
40dB
30dB
20dB
10dB
0dB
-10dB
-20dB
-30dB
-40dB
215
180
135
90
45
0
-45
-90
-135
-180
-215
Figure 12. Small Signal Gain and Phase VS Frequency;
I
K
= 10mA, T
A
= 25
C
I
K
V
IN
9F
15k
8.25k
V
OUT
GND
230
Figure 13. Test Circuit for Gain and Phase Frequency
Response
Figure 14. Frequency = 100kHz, I
K
= 10mA, T
A
= 25
C
Figure 15. Test Circuit for Pulse Response
Figure 16. Stability Boundary Conditions
I
K
V
OUT
GND
250
50
V
IN
f
p = 100kHz
10
0
10
1
10
2
10
3
10
4
10
5
10
6
10
7
100
90
80
70
60
50
40
30
20
10
0
C
L
Load Capacitance (pF)
I
K
Cathode Current (mA)
A: V
KA
= V
REF
B: V
KA
= 5V at I
K
=10mA
C: V
KA
=10V at I
K
=10mA
D: V
KA
=15V at I
K
=10mA
C
D
B
A
STABLE
STABLE
T
A = 25C
6
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2004 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS: Continued
Figure 17. Test Circuit for Stability
Figure 18. Dynamic Output Impedance T
A
= 25
C,
I
K
= 1 to 100mA
Figure 19. Off State Leakage
Figure 20. Shunt Regulator V
OUT
= (1+R1/R2)V
REF
150
10k
I
K
C
L
R
0.01
0.1
1
10
100
-50
0
50
100
150
T
A
Ambient Temperature (C)
I
K
OFF
Cathode Current (nA)
V
KA
= 20V
V
REF
= 0V
1K
10K
100K
1M
10M
100
10
1.0
0.1
0.01
f Frecuency (Hz)
Z
KA
Dynamic Impedance (
)
T
A
= 25C
I
K
= 1 to 100mA
R2
0.1%
V
IN
R3
R1
0.1%
V
OUT
V
REF
SPX2431
Figure 21. Constant Current, Sink, I
SINK
= V
REF
/R1
Figure 22. Reference Amplifier for Isolated Feedback in
Off-Line DC-DC Converters
Q1
V
IN
R2
R1
0.1%
I
SINK
SPX2431
R2
0.1%
R3
R1
0.1%
V
OUT
SPX2431
C2
C1
Isolated
Feedback
V
OUT
RTN
+
R3 sets feedback gain,
C1 provides feedback
compensation
Opto Isolator
7
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2003 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS: Continued
Figure 23. Precision High Current Series Regulator
V
OUT
= (1+R1/R2)V
REF
Figure 25. Single Supply Comparator with Temperature
Compensated Threshold. V
IN
Threshold = 2.5V
V
IN
R1
0.1%
SPX2431
R3
R2
0.1%
C1
R5
R4
V
OUT
V
IN
R1
0.1%
SPX2431
R3
R2
0.1%
Q1
V
OUT
V
CC
R2
SPX2431
V
IN
V
OUT
R1
* Resistor values are chosen such that the effect to
I
REF
is negligible
.
Figure 24. High Current Shunt Regulator
V
OUT
= (1+R1/R2)V
REF
8
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2004 Sipex Corporation
PACKAGES: 3 PIN SOT-23
A
A2
A1
SIDE VIEW
A
A
Seating Plane
C
c
WITH PLATING
BASE METAL
b
E
E1
e
e1
D
b
1
2
3
L1
L
Gauge Plane
VIEW C
SEE VIEW C
B
B
0.89 - 1.12
0.01 - 0.10
Dimensions in (mm)
3 PIN SOT-23
JEDEC TO-236
(AB) Variation
0.88 0.95 1.02
0.30 - 0.50
0.08 - 0.20
0.40 0.50 0.60
0.54 REF
0 - 8
A
A1
A2
b
c
D
E
E1
L
L1
MIN NOM MAX
2.80 2.90 3.04
2.10 - 2.64
1.20 1.30 1.40
e
e1
0.95 BSC
1.90 BSC
SECTION B-B
VIEW A-A
Seating Plane
3 PIN SOT-23
9
Date: 05/25/04 SPX2431 Precision Adjustable Shunt Regulator
Copyright 2003 Sipex Corporation
Corporation
ANALOG EXCELLENCE
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Sipex Corporation
Headquarters and
Sales Office
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
PART NUMBER
ACC
OUTPUT VOLTAGE
PACKAGES
SPX2431AM ...................... 0.5% ...................... 2.5V ......................... 3 Pin SOT-23
SPX2431AM/TR ................ 0.5% ...................... 2.5V ......................... 3 Pin SOT-23
SPX2431M ........................ 1.0% ...................... 2.5V ......................... 3 Pin SOT-23
SPX2431M/TR .................. 1.0% ...................... 2.5V ......................... 3 Pin SOT-23
ORDERING INFORMATION
/TR = Tape and Reel
Pack quantity is 2,500 for SOT-23.
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