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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 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: 0°C to 105°C
■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 (0°C to 105°C) 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 VREF 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
FUNCTIONAL DIAGRAM
+
-
2.5V
Reference
(R)
Anode (A)
Cathode (K)
Now Available in Lead Free Packaging
■ Error Amplifiers
■ Single Supply Amplifier
■ Monitors / VCRs / TVs
■ Personal Computers
SPX2431
3 Pin SOT-23
12
3
Top View
CATHODE
REF
ANODE
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 Sipex Corporation
Cathode-Anode Reverse Breakdown VKA ....................................... 20V
Anode-Cathode Forward Current, (<10ms) IAK ................................. 1A
Operating Cathode Current IKA .................................................. 100mA
Reference Input Current IREF ....................................................... 1.0mA
Continuos Power Dissipation at 25°C PD
SOT-23 .................................................................. 200 mW
Junction Temperature TJ........................................................... 150 °C
Storage Temperature TSTG .............................................. -65 to 150 °C
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
0JA 0JC
TYPICAL DERATING
SOT-23 575°C/W 150°C/W 1.7 mW/°C
Typical deratings of the thermal resistances are given for ambient
temperature >25°.
ELECTRICAL CHARACTERISTICS
Electrical characteristics at 25°C IK = 10mA VK = VREF, unless otherwise specified.
PARAMETER SYMBOL FIGURE CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
SPX2431A SPX2431
Reference Voltage V
REF
22.487 2.500 2.513 2.474 2.500 2.526 V
2T
J
= 0°C to 105°C2.480 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
310V to 20V -2.0 -0.4 0.3 -2.0 -0.4 0.3
Reference Input Current I
REF
30.7 4.0 0.7 4.0 µA
I
REF
Temp Deviation ∆I
REF
3T
J
= 0°C to 105°C0.4 1.2 0.4 1.2 µA
Min I
K
for Regulation I
K(MIN)
20.4 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
2ƒ
z
≤ 1kHz 0.15 0.5 0.15 0.5 Ω
Impedance I
K
= 1 to 100mA
RECOMMENDED CONDITIONS
PARAMETER SYMBOL RATING UNIT
Cathode Voltage VKA VREF to 20 V
Cathode Current IK10 mA
ABSOLUTE MAXIMUM RATINGS
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 Sipex Corporation
0
5000
ppm
0
0.5
%
27ppm/°C
0.0027% / °C
0.0033mV /°C
015 3045 607590105
0
mV
-5
∆T
∆VREF
Junction Temperature (°C)
∆VREF(mV)
∆TA
(
∆VREF at 25°C
)
∆TA
∆VREF x 100
• TC in % / °C =
• TC in mV / °C =
(
∆VREF at 25°C
)
∆TA
∆VREF x 106
• TC in ppm / °C =
CALCULATING AVERAGE TEMPERATURE COEFFICIENT (TC)
Figure 1. VREF 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 VKA = VREF Figure 3. Test Circuit for VKA > VREF Figure 4. Test Circuit for IKOFF
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 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
0°C to 105°C
-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 Voltage (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
VKA Cathode Voltage (V)
IK Cathode Current (µA)
V
KA
= V
REF
0° to 105°C
105°C
25°C
-0°C
-60 -30 0 30 60 90 120
3.0
2.5
2.0
1.5
1.0
0.5
0
TA Ambient Temperature (°C)
IREF Reference Input Current (µA)
R1 = 10kΩ
R2 = ∞
IK = 10mA
Figure 7. Low Current Operating Characteristics
10 100 1K 10K 100K
70
60
50
40
30
20
10
0
f Frequency (Hz)
Noise Voltage n/√Hz
VKA = VREF
IK = 10mA
TA = 25°C
03691215 18 21 24 27 30
0
-10
-20
-30
-40
-50
VKA Cathode Voltage (V)
∆VREF (mV)
0°C
25°C
75°C
125°C
IKA = 10mA
Figure 9. Reference Voltage Line Regulation VS
Cathode Voltage and TAMBIENT
Figure 10. Noise Voltage VS Frequency
Figure 8. Reference Input Current VS Ambient
Temperature
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 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 (Ω)
V
KA
= V
REF
I
K
= 1 to 100mA
f≤1kHz
Figure 11. Low Frequency Dynamic Output Impedance
VS TAMBIENT
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;
IK = 10mA, TA = 25°C
I
K
V
IN
9µF15kΩ
8.25kΩ
V
OUT
GND
230Ω
Figure 13. Test Circuit for Gain and Phase Frequency
Response
Figure 14. Frequency = 100kHz, IK = 10mA, TA = 25°C
Figure 15. Test Circuit for Pulse Response Figure 16. Stability Boundary Conditions
I
K
V
OUT
GND
250Ω
50Ω
V
IN
f
p = 100kHz
100101102103104105106107
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 = 25°C
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 17. Test Circuit for Stability Figure 18. Dynamic Output Impedance TA = 25°C,
IK = 1 to 100mA
Figure 19. Off State Leakage Figure 20. Shunt Regulator VOUT = (1+R1/R2)VREF
150 Ω
10kΩ
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)
VKA = 20V
VREF = 0V
1K 10K 100K 1M 10M
100
10
1.0
0.1
0.01
f Frecuency (Hz)
ZKA Dynamic Impedance (Ω)
TA = 25°C
IK = 1 to 100mA
R2
0.1%
VIN R3
R1
0.1%
VOUT
VREF SPX2431
Figure 21. Constant Current, Sink, ISINK = VREF/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
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 23. Precision High Current Series Regulator
VOUT = (1+R1/R2)VREF
Figure 25. Single Supply Comparator with Temperature
Compensated Threshold. VIN Threshold = 2.5V
VIN
R1
0.1%
SPX2431
R3
R2
0.1%
C1
R5
R4
VOUT
V
IN
R1
0.1%
SPX2431
R3
R2
0.1% Q1
V
OUT
VCC
R2
SPX2431
VIN
VOUT
R1
* Resistor values are chosen such that the effect to
IREF is negligible
.
Figure 24. High Current Shunt Regulator
VOUT = (1+R1/R2)VREF
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 Sipex Corporation
PACKAGES: 3 PIN SOT-23
AA2
A1
SIDE VIEW
A
A
Seating Plane
C
c
WITH PLATING
BASE METAL
b
EE1
e
e1
D
b
12
3
L1
L
Gauge Plane
VIEW C
SEE VIEW C
B
B
SECTION B-B
VIEW A-A
Seating Plane
Ø
SYMBOL MIN NOM MAX
A 0.89 - 1.12
A1 0.01 - 0.1
A2 0.88 0.95 1.02
b 0.3 - 0.5
c 0.08 - 0.2
D 2.8 2.9 3.04
e
e1
E 0.95 - 2.64
E1 1.2 1.3 1.4
L 0.4 0.5 0.6
L1
ø0º-8º
Note: Dimensions in (mm)
3 Pin SOT-23 JEDEC TO-236 (AB) Variation
0.95 BSC
1.90 BSC
0.54 REF
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Date: 1/19/05 SPX2431 Precision Adjustable Shunt Regulator © Copyright 2005 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.
Available in lead free packaging. To order add "-L" suffix to part number.
Example: SPX2431AM/TR = standard; SPX2431AM-L/TR = lead free
CLICK HERE TO ORDER SAMPLES
