TS431I
Adjustable Precision Shunt Regulator
TO-92
SOT-89
Pin Definition:
1. Reference
2. Anode
3. Cathode
SOT-23
Pin Definition:
1. Reference
2. Cathode
3. Anode
SOP-8
Pin Definition:
1. Cathode 8. Reference
2. Anode
7. Anode
3. Anode
6. Anode
4. N/C
5. N/C
General Description
The TS431I/431AI/431BI 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 2.5volt reference makes it
convenient to obtain a stable reference from 5.0volt logic supplies, and since The TS431I/431AI/431BI operates as a
shunt regulator, it can be used as either a positive or negative stage reference.
Features
●
Precision Reference Voltage
TS431I – 2.495V±2%
TS431AI – 2.495V±1%
TS431BI – 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
Ordering Information
Part No.
Package
Packing
TS431xIT B0
TO-92
1Kpcs / Bulk
TS431xIT A3
TO-92
2Kpcs / Ammo
TS431xIX RF
SOT-23
3Kpcs / 7” Reel
TS431xIY RM
SOT-89
1Kpcs / 7” Reel
TS431xIS RL
SOP-8
2.5Kpcs / 2.5” Reel
Note: Where
xx
denotes voltage tolerance
Blank: ±2%
A: ±1%
B: ±0.5%
●
●
●
●
●
●
Application
●
●
●
●
●
●
Voltage Monitor
Delay Timmer
Constant –Current Source/Sink
High-Current Shunt Regulator
Crow Bar
Over-Voltage / Under-Voltage Protection
Block Diagram
Absolute Maximum Rating
(Ta = 25
o
C unless otherwise noted)
Parameter
Cathode Voltage (Note 1)
Continuous Cathode Current Range
Reference Input Current Range
Power Dissipation
Symbol
Vka
Ik
Iref
Limit
Unit
V
mA
mA
W
o
o
37
-100 ~ +150
-0.05 ~ +10
TO-92
0.625
SOT-23
Pd
0.30
SOT-89 / SOP-8
0.50
Junction Temperature
Tj
+150
Operating Temperature Range
Toper
-40 ~ +85
Storage Temperature Range
Tstg
-65 ~ +150
Note 1: Voltage values are with respect to the anode terminal unless otherwise noted.
1/13
C
C
o
C
Version: A07
TS431I
Adjustable Precision Shunt Regulator
Recommend Operating Condition
Parameter
Cathode Voltage (Note 1)
Continuous Cathode Current Range
Symbol
Vka
Ik
Limit
Ref ~ 36
1 ~ 100
Unit
V
mA
Recommend Operating Condition
Parameter
TS431I
Reference voltage
TS431AI
TS431BI
Deviation of reference input
voltage
Radio of change in Vref to
change in cathode Voltage
Reference Input current
Deviation of reference input
current, over temp.
Off-state Cathode Current
Dynamic Output Impedance
Symbo
Vref
∆Vref
∆Vref/∆Vka
Iref
∆Iref
Ika(off)
|Zka|
Test Conditions
Vka =Vref, Ik=10mA (Figure 1)
o
Ta=25 C
Vka =Vref, Ik=10mA (Figure 1)
Ta= full range
Ika=10mA, Vka = 10V to Vref
Vka = 36V to 10V (Figure 2)
R1=10KΩ, R2=
!
, Ika=10mA
Ta= full range (Figure 2)
R1=10KΩ, R2=
!
, Ika=10mA
Ta= full range (Figure 2)
Vref=0V (Figure 3),
Vka=36V
f<1KHz, Vka=Vref
Ika=1mA to 100mA (Figure 1)
Min
2.450
2.475
2.487
--
--
--
--
--
--
--
Typ
2.495
3
-1.4
-1.0
0.7
0.4
--
0.22
Max
2.550
2.525
2.513
17
-2.7
-2.0
4.0
1.2
1.0
0.5
Unit
V
mV
mV/V
uA
uA
uA
Ω
Minimum operating cathode
Ika(min)
Vka=Vref (Figure 1)
--
0.4
0.6
mA
current
* 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.
o
o
o
o
Example: Maximum Vref=2.496V at 30 C, minimum Vref=2.492V at 0 C, Vref=2.495V at 25 C,
ΔT=70
C
Because minimum Vref occurs at the lower temperature, the coefficient is possitive
* The dynamic impedance Z
KA
is defined as:
* 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:
2/13
Version: A07
TS431I
Adjustable Precision Shunt Regulator
Test Circuits
Figure 1: Vka = Vref
Figure 2: Vka > Vref
Figure 3: Off-State Current
Additional Information – Stability
When The TS431I/431AI/431BI is used as a shunt regulator, there are two options for selection of C
L
, 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 TS431I/431AI/431BI 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 TS431I/431AI/431BI 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
3/13
Version: A07
TS431I
Adjustable Precision Shunt Regulator
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
4/13
Version: A07
TS431I
Adjustable Precision Shunt Regulator
Applications Examples (Continue)
Vin
<Vref
>Vref
Vout
V+
≈0.74V
Figure 12: Single-Supply
Comparator with Temperature-
Compensated Threshold
Figure 13: Constant Current Sink
Figure 14: Delay Timer
5/13
Version: A07
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