Features
TL1431
Programmable voltage reference
■ Adjustable output voltage: V
■ Sink current capability: 1 to 100 mA
■ Typical output impedance: 0.22 Ω
■ 0.4% and 0.25% voltage precision
REF
to 36 V
Description
The TL1431 is a programmable shunt voltage
reference with guaranteed temperature stability
over the entire operating temperature range.
The output voltage may be set to any value
between 2.5 V and 36 V with two external
resistors.
The TL1431 operates with a wide current range
from 1 to 100 mA with a typical dynamic
impedance of 0.2 Ω.
Z
TO92
(Plastic package)
D
SO-8
(Batwing plastic micropackage)
March 2008 Rev 4 1/16
www.st.com
16
Schematic diagrams TL1431
1 Schematic diagrams
Figure 1. TO92 pin connections (top view)
Cathode
Figure 2. SO-8 pin connections (top view)
Anode
123
8765
Reference
1 - Cathode
2 - Anode
3 - Anode
4 - N.C.
5 - N.C.
6 - Anode
7 - Anode
8 - Reference
1234
Figure 3. TL1431 block diagram
Cathode
Cathode
Vref
Vref
Vref
Vref
2/16
+
+
-
-
Anode
Anode
TL1431 Absolute maximum ratings and operating conditions
2 Absolute maximum ratings and operating conditions
Table 1. Absolute maximum ratings
Symbol Parameter Value Unit
V
T
ESD
1. Calculated with Tj=+150°C and T
2. Human body model: A 100 pF capacitor is charged to the specified voltage, then discharged through a
3. Machine model: A 200pF capacitor is charged to the specified voltage, then discharged directly between
4. Charged device model: all pins and the package are charged together to the specified voltage and then
Table 2. Operating conditions
Cathode to anode voltage 37 V
KA
I
Continuous cathode current range -100 to +150 mA
k
Reference input current range -0.05 to +10 mA
I
ref
Junction temperature +150 °C
T
j
Power dissipation
P
d
TO92
SO-8 batwing
Storage temperature range -65 to +150 °C
stg
HBM: human body model
MM: machine model
CDM: charged device model
1.5 kΩ resistor between two pins of the device. This is done for all couples of connected pin combinations
while the other pins are floating.
two pins of the device with no external series resistor (internal resistor < 5 Ω). This is done for all couples of
connected pin combinations while the other pins are floating.
discharged directly to the ground through only one pin. This is done for all pins.
(1)
(2)
(3)
=+25°C with relative R
amb
(4)
depending on the package.
thja
625
960
2000
200
1500
mW
V
Symbol Parameter Value Unit
V
Cathode to anode voltage V
KA
I
Cathode current 1 to 100 mA
k
to 36 V
ref
Operating free-air temperature range
T
oper
TL1431C/AC
TL1431I/AI
-20 to +70
-40 to +105
°C
Thermal resistance junction to ambient
R
thja
SO-8 batwing
TO92
130
200
°C/W
3/16
Electrical characteristics TL1431
3 Electrical characteristics
Table 3. T
= 25°C (unless otherwise specified)
amb
TL1431C TL1431AC
Symbol Parameter
Min. Typ. Max. Min. Typ. Max.
Reference input voltage - see Figure 4
ref
ref
ΔT
= V
V
KA
Reference input voltage deviation ov er
temperature range
VKA = V
Temperature coefficient of reference input
voltage
VKA = V
, Ik = 10 mA
ref
, Ik = 10 mA, T
ref
(2)
, Ik = 10 mA, T
ref
(1)
- see Figure 4
≤ T
min
≤T
min
Ratio of change in reference input voltage to
change in cathode to anode voltage - see
Figure 5
= 10mA - ΔVKA = 36V to 3V
I
k
amb
amb
≤ T
≤ T
2.490 2.500 2.510 2.493 2.500 2.507 V
320 320mV
max
±13 ±90 ±13 ±90 ppm/°C
max
-2 -1.1 -2 -1.1 mV/V
ΔV
ΔVref
--------------- -
ΔVref
--------------- -
ΔVka
V
Reference input current
I
ref
= 10mA, R1 = 10kΩ, R2 = ∞
I
k
T
≤ T
amb
≤ T
max
min
1.5 2.5
3
1.5 2.5
Reference input current deviation over
ΔI
I
⏐ Z
1. See Reference input voltage deviation over temperature range in Section 4: Parameter definitions on page 9.
2. See Temperature coefficient of reference input voltage in Section 4: Parameter definitions on page 9.
3. See Dynamic impedance in Section 4: Parameter definitions on page 9.
temperature range
ref
= 10mA, R1 = 10kΩ, R2 =∞, T
I
k
min
≤ T
amb
≤ T
max
Minimum cathode current for regulation - Figure 4
min
I
off
KA
⏐
= V
V
KA
ref
Off-state cathode current - see Figure 6 180 500 180 500 nA
Dynamic impedance
VKA = V
, ΔIk = 1 to100mA, f ≤ 1kHz
ref
(3)
0.2 1.2 0.2 1.2 µA
0.5 1 0.5 0.6 mA
0.20.5 0.20.5 Ω
Unit
µA
3
4/16
TL1431 Electrical characteristics
Table 4. T
= 25°C (unless otherwise specified)
amb
TL1431I TL1431AI
Symbol Parameter
Min. Typ. Max. Min. Typ. Max.
Reference input voltage - see Figure 4
ref
VKA = V
Reference input voltage deviation over
temperature range
ref
V
KA
Temperature coefficient of reference input
voltage
VKA = V
ref
= V
, Ik = 10 mA, T
ref
(2)
, Ik = 10 mA, T
ref
, Ik = 10 mA
(1)
- see Figure 4
≤ T
min
≤ T
min
Ratio of change in reference input voltage to
change in cathode to anode voltage - see
Figure 5
= 10mA - ΔVKA = 36V to 3V
I
k
amb
amb
≤ T
≤ T
2.490 2.500 2.510 2.493 2.500 2.507 V
730 730mV
max
±22 ±100 ±22 ±100 ppm/°C
max
-2 -1.1 -2 -1.1 mV/V
ΔV
ΔVref
--------------- -
ΔVref
--------------- -
ΔVka
V
ΔT
Reference input current
I
ref
= 10mA, R1 = 10kΩ, R2 = ∞
I
k
≤ T
T
min
amb
≤ T
max
1.5 2.5
3
1.5 2.5
Reference input current deviation over
ΔI
temperature range
ref
= 10mA, R1 = 10kΩ, R2 =∞, T
I
k
min
≤ T
amb
≤ T
max
0.5 1 0.8 1.2 µA
Minimum cathode current for regulation - see
I
I
⏐ Z
1. See Reference input voltage deviation over temperature range in Section 4: Parameter definitions on page 9.
2. See Temperature coefficient of reference input voltage in Section 4: Parameter definitions on page 9.
3. See Dynamic impedance in Section 4: Parameter definitions on page 9.
Figure 4
min
off
KA
⏐
= V
V
KA
ref
Off-state cathode current - see Figure 6 180 500 180 500 nA
Dynamic impedance
VKA = V
, ΔIk= 1 to100mA, f ≤ 1kHz
ref
(3)
0.5 1 0.5 0.7 mA
0.20.5 0.20.5 Ω
Unit
µA
3
5/16