TS431-Z
Adjustable Precision Shunt Regulator
SOT-23
TS431-Z
Pin Definition:
1. Reference
2. Cathode
3. Anode
TS431AR-Z
Pin Definition:
1. Cathode
2. Reference
3. Anode
General Description
TS431 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 to 250mA with a typical dynamic
impedance of 0.2Ω. 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 2.495V reference makes it
convenient to obtain a stable reference from 5.0V logic supplies, and since The TS431 operates as a shunt
regulator, it can be used as either a positive or negative stage reference.
Features
●
●
●
●
●
●
●
●
Programmable Output Voltage up to 36V
TS431A – V
REF
2.495V ±1% tolerance
TS431B – V
REF
2.495V ±0.5% tolerance
Fast Turn-On Response
Sink Current Capability: 200mA
Low Dynamic Output Impedance: 0.2Ω (Typ)
Min. Operating Cathode Current: 0.2mA (Typ)
Halogen Free
Ordering Information
Part No.
TS431ACX-Z RFG
TS431ARCX-Z RFG
Package
SOT-23
SOT-23
Packing
3kpcs / 7” Reel
3kpcs / 7” Reel
TS431BCX-Z RFG
SOT-23
3kpcs / 7” Reel
Note:
“G” denotes for Halogen- and Antimony-free as those which
contain <900ppm bromine, <900ppm chlorine (<1500ppm total
Br + Cl) and <1000ppm antimony compounds
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
Operating Temperature Range
Junction Temperature
Storage Temperature Range
Thermal Resistance Junction to Ambient
Symbol
V
KA
I
K
I
REF
P
D
T
OPER
T
J
T
STG
R
ӨJA
2
Limit
36
+250
10
0.25
-20 ~ +85
-40 ~ +125
-40 ~ +125
156
Unit
V
mA
mA
W
o
o
o
o
C
C
C
C/W
Note: R
ӨJA
is measured with the PCB copper area of approximately 1 in (Multi-Layer)
1/10
Version: C14
TS431-Z
Adjustable Precision Shunt Regulator
Electrical Characteristics
(T
A
=25
o
C, unless otherwise specified)
Parameter
Reference
voltage
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
current
TS431A
TS431B
Symbol
V
REF
∆
V
REF
∆V
REF
/∆V
KA
I
REF
∆I
REF
I
KA
(off)
| Z
KA
|
I
KA
(min)
Test Conditions
V
KA
=V
REF
, I
K
=10mA (Figure 1)
V
KA
= V
REF
, I
K
=10mA (Figure 1)
T
A
=-20~85 C
I
KA
=10mA,
(Figure 2)
(Figure 2)
R1=10KΩ, R2=
∞
, I
KA
=10mA
T
A
=-20~85 C (Figure 2)
V
REF
=0V (Figure 3), V
KA
=36V
f<1KHz, V
KA
= V
REF
(Figure 1)
V
KA
= V
REF
(Figure 1)
o
o
Min
2.470
2.483
--
--
--
--
--
--
--
--
Typ
2.495
6
-1.2
-1.0
1.5
0.4
0.1
0.2
0.2
Max
2.520
2.507
20
-2.0
-2.0
3.5
1.2
1.0
0.5
0.5
Unit
V
mV
mV/V
µA
µA
µA
Ω
mA
Deviation of reference input
V
KA
= 10V to V
REF
V
KA
= 36V to 10V
R1=10KΩ, R2=
∞
, I
KA
=10mA
* 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.
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
o
o
o
o
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)
2/10
Version: C14
TS431-Z
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 TS431A/431B is used as a shunt regulator, there are two options for selection of C
L
, are recommended for optional
stability:
A)
B)
No load capacitance across the device, decouple at the load.
Large capacitance across the device, optional decoupling at the load.
The reason for this is that TS431A/431B 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 TS431A/431B 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.
3/10
Version: C14
TS431-Z
Adjustable Precision Shunt Regulator
Applications Examples (Continue)
Figure 4: Voltage Monitor
Figure 5: Output Control for Three Terminal
Fixed Regulator
Figure 6: Shunt Regulator
Figure 7: High Current Shunt Regulator
Figure 8: Series Pass Regulator
Figure 9: Constant Current Source
4/10
Version: C14
TS431-Z
Adjustable Precision Shunt Regulator
Applications Examples (Continue)
Figure 10: TRIAC Crowbar
Figure 11: SCR Crowbar
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
5/10
Version: C14
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