TL431 Programmable Precision Reference
T
he TL431 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. This device exhibits a
wide operating current range of 1.0 to 100 mA 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 2.5 volt
reference makes it convenient to obtain a stable reference from 5.0 volt logic supplies, and
since the TL431 operates as a shunt regulator, it can be used as either a positive or negative
voltage reference
FEATURE
1.
Programmable Output Voltage to 36 Volts
2.
Low Dynamic Output Impedance,0.22Ω Typical
3.
Sink Current Capability of 1.0 to 100mA
4.
Equivalent Full-Range Temperature
Coefficient of 50ppm/℃ Typical
5.
Temperature Compensated for Operation over
Full Rated Operating Temperature Range
6.
Low Output Noise Voltage
REFERENCE
ANODE
CATHODE
TO-92 TOP VIEW
ANODE
REF
CATHODE
SOT-23 TOP VIEW
REF
ANODE CATHODE
SOT-89 TOP VIEW
1
CATHODE
NC
NC
1
8
REF
NC
ANODE
NC
CATHODE
ANODE
8
REF
ANODE
ANODE
ANODE
NC
NC
NC
DIP-8 TOP VIEW
SOP-8 TOP VIEW
1
2001-05-A
TL431 Programmable Precision Reference
BLOCK DIAGRAM
Cathode
(K)
Cathode
(K)
800
800
Ref erence
(R)
Ref erence
20pF
(R)
Anode
(A)
SYMBOL
150
3.28K
4.0K
10K
2.4K
7.2K
20pF
Cathode(K)
Ref erence(R)
+
-
1.0K
2.5Vref
800
Anode(A)
Representative Block Diagram
Anode
(A)
ABSOLUTE MAXIMUM RATINGS
(Full operating ambient temperature range applies, unless otherwise noted)
Rating
Cathode To Anode Voltage
Cathode Current Range, Continuous
Reference Input Current Range,
Continuous
Operating Junction Temperature
Operating Ambient Temperature Range
TL431CT/CP/CD/CH/CLT1
Storage temperature Range
Total Power Dissipation @T
A
=25℃
Derate above 25℃ Ambient
Temperature
T,D Suffix Package
P Suffix Package
H Suffix Package
LT1 Suffix Package
P
D
0.70
1.10
1.0
0.28
W
T
A
T
stg
-20 ~ +85
-65 to +150
℃
℃
Symbol
V
KA
I
K
I
ref
T
J
Value
37
-100 to +150
-0.05 to +10
150
Unit
V
mA
mA
℃
2
2001-05-A
TL431 Programmable Precision Reference
Total Power Dissipation @T
C
=25℃
Derate above 25℃ Case Temperature
T,D Suffix Package
P Suffix Package
H Suffix Package
LT1 Suffix Package
P
D
1.5
3.0
W
THERMAL CHARACTERISTICS
Characteristics
Thermal Resistance, Junction to Ambient
Thermal Resistance, Junction to Case
Symbol
R
θ
JA
R
θ
JC
T,D
P
H
LT1
Suffix Suffix Suffix Suffix
178
83
114
41
110
8
575
150
Unit
℃/W
℃/W
RECOMMENDED OPERATING CONDITIONS
Condition/Value
Cathode to Anode Voltage
Cathode Current
Symbol
V
KA
I
K
Min
V
ref
1.0
Max
36
100
Unit
V
mA
ELECTRICAL CHARACTERISTICS(
Ambient temperature at 25℃ unless otherwise noted)
Characteristic
Reference Input Voltage (Fig 1)
V
KA
=V
ref
, I
K
=10mA
T
A
=+25℃ Tolerance 0.5%
1%
2%
T
A
=T
low
to T
high
(Note 1)
Reference Input Voltage Deviation Over
Temperature Range (Fig 1, Note 1,2)
V
KA
=V
ref
. I
K
=10mA
Ratio of Change in Reference Input Voltage
To Change in Cathode to Anode Voltage
I
K
=10mA (Figure 2),
ΔV
KA
=10V to V
ref
ΔV
KA
=36V to 10V
ΔV
ref
--
3.0
17
mV
V
ref
2.483
2.470
2.445
2.453
--
2.495
2.507
2.520
2.55
2.537
V
Symbol
TL431
Min
Typ
Max
Unit
∆
V
ref
∆
V
KA
--
--
-1.4
-1.0
-2.7
-2.0
mV/V
3
2001-05-A
TL431 Programmable Precision Reference
Reference Input Current (Figure 2)
I
K
=10mA, R1=10k, R2=∞
T
A
=+25℃
T
A
=T
low
to T
high
(Note 1)
Reference Input Current Deviation Over
Temperature Range (Figure 2, Note 1)
I
K
=10mA, R1=10k, R2=∞
Minimum Cathode Current for Regulation
V
KA
=V
ref
(Figure 1)
Off-State Cathode Current (Figure 3)
V
KA
=36V, V
ref
=0V
Dynamic Impedance (Figure 1, Note 3)
V
KA
=V
ref
,
ΔI
K
=1.0mA to 100mA, f< 1.0kHz
I
min
--
0.5
1.0
mA
ΔI
ref
--
0.4
1.2
µA
I
ref
--
--
1.8
--
4.0
5.2
µA
I
off
--
260
1000
nA
|Z
KA
|
--
0.22
0.5
Ω
1
T
low
=0℃,
2
The deviation parameter
ΔV
ref
is defined as the differences between the maximum and
minimum values obtained over the full operating ambient temperature range the applies.
T
high
=+70℃
The average temperature coefficient of the reference input voltage,
αV
ref
, is defined as:
∆
V
ref
×
10
6
ppm
V
ref
@ 25
°
C
∆
V
ref
×
10
6
αV
ref
=
=
∆
T
A
(
V
ref
@ 25
°
C
)
°
C
∆
T
A
αV
ref
can be positive or negative depending on whether V
ref
Min of V
ref
Max occurs at the
lower ambient temperature. (Refer to Figure 6)
Example:
ΔV
ref
=8.0mV and slope is positive, V
ref
@25℃=2.495V,
ΔT
A
=70℃
0.008
×
10
6
αV
ref
=
=45.8 ppm/℃
70(2.495)
4
2001-05-A
TL431 Programmable Precision Reference
3
The dynamic impedance Z
KA
is defined as:
| Z
KA
| =
∆
V
KA
∆
I
K
When the device is programmed with two external resistors, R1 and r2, (refer to Figure 2)
the total dynamic impedance of the circuit is defined as:
| Z
KA
’|
≈
| Z
KA
| (1+
R
1
)
R
2
5
2001-05-A
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