TS1431
Adjustable Precision Shunt Regulator
1/10 Version: C07
SOT-23
General Description
TS1431 series integrated circuits are three-terminal programmable shunt regulator diodes. These monolithic IC voltage
references operate as a low temperature coefficient zener which is programmable from Vref to 36 volts with two
external resistors. These devices exhibit a wide operating current range of 1.0 to 100mA with a typical dynamic
impedance of 0.22Ω. The characteristics of these references make them excellent replacements for zener diodes in
many applications such as digital voltmeters, power supplies, and op amp circuitry. The 2.5V reference makes it
convenient to obtain a stable reference from 5.0V logic supplies, and since The TS1431 series operates as a shunt
regulator, it can be used as either a positive or negative stage reference.
Features
● Precision Reference Voltage
TS1431 – 2.495V±2%
TS1431A – 2.495V±1%
TS1431B – 2.495V±0.5%
● Equivalent Full Range Temp. Coefficient: 50ppm/ ºC
● Programmable Output Voltage up to 36V
● Fast Turn-On Response
● Sink Current Capability of 1~100mA
● Low Dynamic Output Impedance: 0.2Ω
● Low Output Noise
Part No.
Package
Packing
TS1431xCX RF
SOT-23
3Kpcs / 7” Reel
TS1431xCX RFG
SOT-23
3Kpcs / 7” Reel
Application
● Voltage Monitor
● Delay Timmer
● Constant –Current Source/Sink
● High-Current Shunt Regulator
● Crow Bar
● Over-Voltage / Under-Voltage Protection
Absolute Maximum Rating (Ta = 25oC unless otherwise noted)
Parameter
Symbol
Limit
Unit
Cathode Voltage
Vka
36
V
Continuous Cathode Current Range
Ik
1 ~ +100
mA
Reference Input Current Range
Iref
-0.05 ~ +10
mA
Power Dissipation
Pd
0.30
W
Junction Temperature
Tj
+150
oC
Operating Temperature Range
Toper
0 ~ +70
oC
Storage Temperature Range
Tstg
-65 ~ +150
oC
Pin Definition:
1. Cathode
2. Reference
3. Anode
TS1431
Adjustable Precision Shunt Regulator
2/10 Version: C07
Recommend Operating Condition
Parameter
Symbol
Limit
Unit
Cathode Voltage (Note 1)
VKA
Ref ~ 36
V
Continuous Cathode Current Range
IK
1 ~ 100
mA
Recommend Operating Condition
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
TS1431
2.450
2.550
TS1431A
2.475
2.525
Reference voltage
TS1431B
VREF
VKA =VREF, IK =10mA (Figure 1)
Ta=25oC
2.487
2.495
2.513
V
Deviation of reference input
voltage
∆ VREF
VKA = VREF, IK =10mA (Figure 1)
Ta= full range
--
3
17
mV
Radio of change in Vref to
change in cathode Voltage
∆VREF /∆VKA
IKA =10mA, VKA = 10V to VREF
VKA = 36V to 10V (Figure 2)
--
--
-1.4
-1.0
-2.7
-2.0
mV/V
Reference Input current
IREF
R1=10KΩ, R2=
∞
, IKA =10mA
Ta= full range (Figure 2)
--
0.7
4.0
uA
Deviation of reference input
current, over temp.
∆IREF
R1=10KΩ, R2=
∞
, IKA =10mA
Ta= full range (Figure 2)
--
0.4
1.2
uA
Off-state Cathode Current
IKA (off)
VREF =0V (Figure 3),
VKA =36V
--
--
1.0
uA
Dynamic Output Impedance
| ZKA |
f<1KHz, VKA = VREF
IKA =1mA to 100mA (Figure 1)
--
0.22
0.5
Ω
Minimum operating cathode
current
IKA (min)
VKA = VREF (Figure 1)
--
0.4
0.6
mA
* The deviation parameters ∆VREF and ∆IREF are defined as difference between the maximum value and minimum value
obtained over the full operating ambient temperature range that applied.
* The average temperature coefficient of the
reference input voltage, αVREF is defined as:
Where: T2-T1 = full temperature change.
αVREF can be positive or negative depending on whether the slope is positive or negative.
Example: Maximum VREF=2.496V at 30oC, minimum VREF =2.492V at 0oC, VREF =2.495V at 25oC, ΔT=70oC
αVREF | = [4mV / 2495mV] * 106 / 70oC ≈ 23ppm/oC
Because minimum VREF occurs at the lower temperature, the coefficient is positive.
* The dynamic impedance ZKA is defined as:
| ZKA | = ΔVKA / ΔIKA
* When the device operating with two external resistors, R1 and R2, (refer to Figure 2) the total dynamic impedance of
the circuit is given by:
| ZKA | = Δv / Δi | ≈ ZKA | * ( 1 + R1 / R2)
TS1431
Adjustable Precision Shunt Regulator
3/10 Version: C07
Test Circuits
Figure 1: VKA = VREF
Figure 2: VKA > VREF
Figure 3: Off-State Current
Additional Information – Stability
When The TS1431/1431A/1431B is used as a shunt regulator, there are two options for selection of CL, are
recommended for optional stability:
A) No load capacitance across the device, decouple at the load.
B) Large capacitance across the device, optional decoupling at the load.
The reason for this is that TS1431/1431A/1431B exhibits instability with capacitances in the range of 10nF to 1uF
(approx.) at light cathode current up to 3mA (typ). The device is less stable the lower the cathode voltage has been set
for. Therefore while the device will be perfectly stable operating at a cathode current of 10mA (approx.) with a 0.1uF
capacitor across it, it will oscillate transiently during start up as the cathode current passes through the instability region.
Select a very low capacitance, or alternatively a high capacitance (10uF) will avoid this issue altogether. Since the user
will probably wish to have local decoupling at the load anyway, the most cost effective method is to use no capacitance
at all directly across the device. PCB trace/via resistance and inductance prevent the local load decoupling from
causing the oscillation during the transient start up phase.
Note: if the TS1431/1431A/1431B is located right at the load, so the load decoupling capacitor is directly across it, then
this capacitor will have to be ≤1nF or ≥10uF.
Applications Examples
Figure 4: Voltage Monitor
Figure 5: Output Control for Three Terminal
Fixed Regulator
TS1431
Adjustable Precision Shunt Regulator
4/10 Version: C07
Applications Examples (Continue)
Figure 6: Shunt Regulator
Figure 7: High Current Shunt Regulator
Figure 8: Series Pass Regulator
Figure 9: Constant Current Source
Figure 10: TRIAC Crowbar
Figure 11: SCR Crowbar
TS1431
Adjustable Precision Shunt Regulator
5/10 Version: C07
Applications Examples (Continue)
Vin
Vout
<Vref
V+
>Vref
≈0.74V
Figure 12: Single-Supply Comparator with
Temperature-Compensated Threshold
Figure 13: Constant Current Sink
Figure 14: Delay Timer
TS1431
Adjustable Precision Shunt Regulator
6/10 Version: C07
Typical Performance Characteristics
Test Circuit for Voltage Amplification
Figure 14: Small-Signal Voltage Gain and Phase Shirt vs. Frequency
Test Circuit for Reference Impedance
Figure 15: Reference Impedance vs. Frequency
TS1431
Adjustable Precision Shunt Regulator
7/10 Version: C07
Typical Performance Characteristics (Continue)
The areas under the curves represent conditions that may
cause the device to oscillate. For curves B, C, and D, R2
and V+ were adjusted to establish the initial VKA and IKA
conditions with CL=0. VBATT and CL then were adjusted to
determine the ranges of stability.
Test Circuit for Curve A
Test Circuit for Curve B, C and D
Figure 16: Stability Boundary Condition
Test Circuit for Pulse Response, Ik=1mA
Figure 17: Pulse Response
TS1431
Adjustable Precision Shunt Regulator
8/10 Version: C07
Electrical Characteristics
Figure 18: Reference Voltage vs. Temperature
Figure 19: Reference Current vs. Temperature
Figure 20: Cathode Current vs. Cathode Voltage
TS1431
Adjustable Precision Shunt Regulator
9/10 Version: C07
SOT-23 Mechanical Drawing
Marking Diagram
1
= Device Code
X
= Tolerance Code
(A = ±1%, B = ±0.5%, C = ±2%,)
Y
= Year Code
M
= Month Code
(A=Jan, B=Feb, C=Mar, D=Apl, E=May, F=Jun, G=Jul, H=Aug, I=Sep,
J=Oct, K=Nov, L=Dec)
L
= Lot Code
SOT-23 DIMENSION
MILLIMETERS
INCHES
DIM
MIN
MAX
MIN
MAX.
A
0.95 BSC
0.037 BSC
A1
1.9 BSC
0.074 BSC
B
2.60
3.00
0.102
0.118
C
1.40
1.70
0.055
0.067
D
2.80
3.10
0.110
0.122
E
1.00
1.30
0.039
0.051
F
0.00
0.10
0.000
0.004
G
0.35
0.50
0.014
0.020
H
0.10
0.20
0.004
0.008
I
0.30
0.60
0.012
0.024
J
5º
10º
5º
10º
TS1431
Adjustable Precision Shunt Regulator
10/10 Version: C07
Notice
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assumes no responsibility or liability for any errors or inaccuracies.
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