TS1431
Adjustable Precision Shunt Regulator
SOT-23
Pin Definition:
1. Cathode
2. Reference
3. Anode
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 V
REF
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
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
Ordering Information
Part No.
Package
Packing
TS1431xCX RFG
SOT-23
3,000pcs / 7” Reel
Note: “G” denote for Green Product
Where
xx
denotes voltage tolerance
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 Ratings
(T
A
= 25
o
C unless otherwise noted)
Parameter
Cathode Voltage
Continuous Cathode Current Range
Reference Input Current Range
Power Dissipation
Junction Temperature
Operating Temperature Range
Storage Temperature Range
Symbol
V
KA
I
KA
I
REF
P
D
T
J
T
OPR
T
STG
Limit
36
1 ~ +100
-0.05 ~ +10
0.30
+150
0 ~ +70
-65 ~ +150
Unit
V
mA
mA
W
C
o
C
o
C
o
Document Number: DS_P0000229
1
Version: E15
TS1431
Adjustable Precision Shunt Regulator
Recommended Operating Condition
Parameter
Cathode Voltage
(Note 1)
Symbol
V
KA
I
K
Limit
Ref ~ 36
1 ~ 100
Unit
V
mA
Continuous Cathode Current Range
Electrical Characteristics
Parameter
Reference voltage
TS1431A
TS1431B
Symbol
V
REF
∆
V
REF
∆V
REF
/∆V
KA
I
REF
∆I
REF
I
KA
(off)
| Z
KA
|
Test Conditions
V
KA
=V
REF
, I
K
=10mA (Figure 1)
T
A
=25 C
V
KA
= V
REF
, I
K
=10mA (Figure 1)
T
A
= full range
I
KA
=10mA, V
KA
= 10V to V
REF
V
KA
= 36V to 10V (Figure 2)
R1=10KΩ, R2=
∞
, I
KA
=10mA
T
A
= full range (Figure 2)
R1=10KΩ, R2=
∞
, I
KA
=10mA
T
A
= full range (Figure 2)
V
REF
=0V (Figure 3),
V
KA
=36V
f<1KHz, V
KA
= V
REF
I
KA
=1mA to 100mA (Figure 1)
o
Min
2.475
2.487
--
--
--
--
--
--
--
Typ
2.495
3
-1.4
-1.0
0.7
0.4
--
0.22
Max
2.525
2.513
17
-2.7
-2.0
4.0
1.2
1.0
0.5
Unit
V
mV
mV/V
µA
µA
µA
Ω
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
Minimum operating cathode
I
KA
(min)
V
KA
= V
REF
(Figure 1)
--
0.4
0.6
mA
current
* The deviation parameters
∆V
REF
and
∆I
REF
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,
αV
REF
is defined as:
Where:
T2-T1
= full temperature change.
αV
REF
can be positive or negative depending on whether the slope is positive or negative.
o
o
o
o
Example: Maximum V
REF
=2.496V at 30 C, minimum V
REF
=2.492V at 0 C, V
REF
=2.495V at 25 C,
∆T=70
C
αV
REF
| = [4mV / 2495mV] * 10
6
/ 70
o
C
≈
23ppm/
o
C
Because minimum V
REF
occurs at the lower temperature, the coefficient is positive.
* The dynamic impedance Z
KA
is defined as:
| Z
KA
| =
∆V
KA
/
∆I
KA
* 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:
| Z
KA
| =
∆v
/
∆i
|
≈
Z
KA
| * ( 1 + R1 / R2)
Document Number: DS_P0000229
2
Version: E15
TS1431
Adjustable Precision Shunt Regulator
Test Circuits
Figure 1: V
KA
= V
REF
Figure 2: V
KA
> V
REF
Figure 3: Off-State Current
Additional Information – Stability
When The TS1431A/1431B 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 TS1431A/1431B exhibits instability with capacitances in the range of 10nF to 1µF (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 0.1µF
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 (10µF) 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 TS1431A/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
≥10µF.
Applications Examples
Figure 4: Voltage Monitor
Figure 5: Output Control for Three Terminal
Fixed Regulator
3
Version: E15
Document Number: DS_P0000229
TS1431
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
Document Number: DS_P0000229
4
Version: E15
TS1431
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
Document Number: DS_P0000229
5
Version: E15
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