TLV431
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TLV431
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1.24V COST EFFECTIVE SHUNT REGULATOR
Description
The TLV431 is a three terminal adjustable shunt regulator offering
excellent temperature stability and output current handling capability
up to 20mA. The output voltage may be set to any chosen voltage
between 1.24 and 18 volts by selection of two external divider
resistors.
The TLV431 can be us ed as a rep lac ement for zener diodes in m any
applicat i ons requiri ng an improvement in zener performanc e.
The TLV431 is available in 3 grades with initial tolerances of 1%,
0.5%, and 0.2% for the A, B and T grades respectively.
Features
• Low Voltage Operation VREF = 1.24V
• Temperature range -40 to +125°C
• Reference Voltage T olerance at +25°C
0.2% TLV431T
0.5% TLV431B
1% TLV431A
• Typical temperature drift
4 mV (0°C to +70°C)
6 mV (-40°C to +85°C)
11mV (-40°C to +125°C)
• 80µA Minimum cathode current
• 0.25Ω Typical Output Impedance
• Adjustable Output Voltage V REF to 18V
• Lead-Free Finish; RoHS Compliant (Notes 1 & 2)
• Halogen and Antimon y Free. “Green” Device (Note 3)
• Qualified to AEC-Q100
Typical Application Circuit
3.3 V
Secondary side
regulated supply
Primary side
controller
R3
IF
R1
R2
TLV431
GND
Optocoupler
Pin Assignments
TLV431_H6 (SC70-6 [SOT363])
(Top View)
TLV431_F (SOT23)
(Top View)
TLV431_E5 (SOT25)
(Top View)
‡ Pin should be left floating or connect to anode
Notes: 1. EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. All applicable RoHS exemptions applied.
2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
5 ANODE
N/C 1
CATHODE 3
N/C‡ 2
4 REF
3 ANODE
REF 1
CATHODE 2
6 ANODE
CATHODE 1
REF 3
N/C‡ 2
4 NC
5 NC‡
TLV431
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Absolute Ma ximum Ratings (@TA = +25°C, unless otherwise specifi ed. )
Symbol Parameter Rating Unit
VKA Cathode Voltage 20 V
IKA Continuous Cat hode Current -20 to +20 mA
IREF Referenc e I nput Current Range -0.05 to +3 mA
VIN Input Supply Voltage (Relative to Ground) -0.03 to +18 V
ESD Susceptibility
HBM Human Body Model 4 kV
MM Machine Model 400 V
CDM Charged Device Model 1 kV
(Semiconductor devices are ESD sensitive and may be damaged by expo sure to ESD events. Suitable ESD precautions should be taken when handling and
transp orti ng th es e devices.)
Parameter Rating Unit
Operating Junction Tem perature -40 to +150 °C
Storage Temperature -65 to +150 °C
Operation above the absolute maximum rating may cause device failure.
Operation at the absolute maximum ratings, for extended periods, may reduce device reliability.
Unless otherwise stated voltages specified are relative to the ANODE pin.
These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure.
Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.)
Symbol Parameter Min Max Units
VKA Cathode Voltage VREF 18 V
IKA Cathode Current 0.1 15 mA
TA Operating Ambient Temperat ure Range -40 +125 °C
Package Thermal Data
Package
θ
JA PDIS
TA = +25°C, TJ = +150°C
SOT23 380°C/W 330mW
SOT25 250°C/W 500mW
SC70-6
(SOT363) 380°C/W 330mW
TLV431
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Electrical Characteristics (@TA = +25°C, unless otherwise specifi ed. )
Symbol Parameter Conditions Min Typ Max Units
VREF Reference Voltage
VKA = VREF,
TA = +25°C
TLV431A 1.228 1.24 1.252
V
TLV431B 1.234 1.24 1.246
TLV431T 1.2375 1.24 1.2425
VKA = VREF,
TA = 0 to +70°C
TLV431A 1.221 1.259
TLV431B 1.227 1.253
TLV431T 1.230 1.250
VKA = VREF,
TA = -40 to +85°C
TLV431A 1.215 1.265
TLV431B 1.224 1.259
TLV431T 1.228 1.252
VKA = VREF,
TA = -40 to +125°C
TLV431A 1.209 1.271
TLV431B 1.221 1.265
TLV431T 1.224 1.255
VREF(dev) Deviation of reference
voltage over full
temperature range VKA = VREF TA = 0 to +70°C 4 12 mV
TA = -40 to +85°C 6 20
TA = -40 to +125°C 11 31
ΔVREF
ΔVKA
Ratio of change in
reference voltage to the
change in cathode
voltage VKA for VREF to 6V -1.5 -2.7 mV/V
18V -1.5 -2.7
IREF Referenc e I nput Current R1 = 10kΩ, R2 = OC 0.15 0.5 µA
IREF(dev) IREF deviation over full
temperature range R1 = 10kΩ,
R2 = OC
TA = 0 to +70°C 0.05 0.3 µA
TA = -40 to +85°C 0.1 0.4
TA = -40 to +125°C 0.15 0.5
IKMIN Minimum cathode
current for regulati on VKA = VREF TA = 0 to +70°C 55 80 µA
TA = -40 to +85°C 55 80
TA = -40 to +125°C 55 100
IK(OFF) Off state current VKA = 18V, VREF = 0 V 0.001 0.1 µA
ZKA Dynamic output
impedance VKA = VREF, f = <1kHz
IK = 0. 1 t o 15mA 0.25 0.4 Ω
TLV431
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Typical Characteristics (cont.)
Test Circuit for Input Noise Voltage
Test Circuit for Phase Shift and Gain
Test Circuit for Reference Impedance
100µF
50Ω
100Ω
O/P
100Ω
~
~
10µF
4.3kΩ
O/P
6.8kΩ
180Ω
5V
IK
470µF
750Ω
O/P
1kΩ
3V
TLV431
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Applic ation Notes
In a conventional shunt regulator application (Figure 1), an external series resistor (R3) is connected between the supply voltage, VIN, and the
TLV431.
R3 determines the current that flows through the load (IL) and the TLV431 (IK). The TLV431 will adjust how much current it sinks or “shunts” to
maintain a voltage equal to VREF across its feedback pin. Since load current and s upply voltage may vary, R3 shoul d be small enough to supply
at least the minimum acceptable IKMIN to the TLV431 even when the supply voltage is at its minimum and the load current is at its maximum
value. When the supply voltage is at its maximum and IL is at its minimum, R3 should be large enough so that the current flowing through the
TLV431 is less than 15mA.
R3 is determined by the supply voltage, (VIN), the load and operating current, (IL and IK), and the TLV431’s reverse breakdown voltage, VKA.
R3
Vin Vout
V
I
K
IL
R1
R2
TLV431
GND
C1
0.1µF
REF
Figure 1
KL
KAIN
3
II VV
R+
−
=
where
+×= 2
1
REFKA R
R
1VV
and VKA = VOUT
The values of R1 and R2 shoul d be large enough so that the current flowing through them is much smaller than t he current through R3 yet not
too large that the voltage drop across them caused IREF affects the reference accuracy.
The most f requent applic ation of the TLV431 is in isolat ed low output voltage po wer supplies where the regulat ed output is galvanically is olated
from the controller. As shown in Figure 2 the T LV431 drives current , IF, through the opto-c oupl er’s LED which in turn drives the isol ated transi st or
which is connected to the controller on the primary side of the power supply.
This completes the feedback path through the isolation barrier and ensures that a stable is olated supply is maint ained.
Assuming a forward drop of 1.4V across the opto-coupler diode allows output volt ages as low as 2.7V to be regulated.
Regulated SupplyRegulated Supply
To controller
To controller
R3
I
F
R1
R2
TLV431
GND
Optocoupler
+= 2R1R
1VV
REFOUT
mA15 7.2V
3R
I7.2V
(max)OUT
(min)F
OUT
−
≥>
−
Figure 2. Using the TLV431 as the Regulating Element in an Isolated PSU
TLV431
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Applic ation Notes (cont.)
Printed Circuit Board Layout Considerations
The TLV431 in the SOT25 package has t he die attached to pin 2, which res ults in an electrical cont act between pin 2 and pin 5. Therefore, pin 2
of the SOT25 package must be left floating or connected to pin 5.
TLV431 in the SC70-6 (S OT363) pack age has the die att ached to pin 2 and 5, which res ults i n an electrical cont act between pins 2, 5 and pin 6.
Therefore, pins 2 and 5 must be left floating or connected to pin 6.
Other Applications of the TLV431
R4
V
in
V
out
I
B
R1
R2
TLV431
GND
C1
0.1µF
ZXTP2039F
Q1
R3
I
SH
V
REF
+= 2R1R
1VV REFOUT
BSH
OUTIN II VV
3R +
−
=
B
BE
I
V
4R =
mA15I
hI
B
(min)FE
SH
≤<
Figure 3. High Current Shunt Regulator
It may at times be required to shunt-regulate more current than the 15mA that the TLV431 is capable of.
Figure 3 shows how this can be done using transistor Q1 to amplify the TLV431’s current. Care needs to be taken that the power dissipation
and/or SOA requirements of the transi st or is not exceeded.
R3
Vin Vout
V
I
B
I
OUT
R1
R2
TLV431
GND
C1
0.1µF
REF
ZXTN25020CFH
Q1
+= 2R1R
1VV
REFOUT
B
BEOUTIN
I)VV(V
3R +−
=
mA15I
h
I
B
(min)FE
(max)OUT
≤<
Figure 4. Basic Series Regulator
A very effect ive and simple seri es regulator can be im plemented as shown in Fi gure 4 above. This may be p referable if the load requires more
current than c an be provided by t he TLV431 alone and t here is a need t o conserve po wer when the l oad is not being po wered. This c ircuit also
uses one component less than the shunt circuit shown in Figure 3 above.
TLV431
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Applic ation Notes (cont.)
Printed Circuit Board Layout Considerations (cont.)
R3
V
in
V
out
V
I
B
I
OUT
R1
R2
TLV431
GND
C1
0.1µF
REF
ZXTN25020CFH
Q1
V
REF
R
S
TLV431
+= 2R1R
1VV REFOUT
B
BEOUTIN
I)VV(V
3R +−
=
mA18I
h
IB
(min)FE
(max)OUT ≤<
(max)OUT
REF
S
IV
R=
Figure 5. Series Regulator with Current Limit
Figure 5 adds current limit to the series regulator in Figure 4 using a second TLV431. For currents below the limit, the circuit works normally
supplying the required load current at the design voltage. However should attempts be made to exceed the design current set by the second
TLV431, the device begins to shunt current away from the base of Q1. This begins to reduce the output voltage and thus ensuring that the out put
current is clamped at the desi gn value. Subject only to Q1’s ability to withstand the result ing power dissipation, the circ uit can withstand eit her a
brief or indefinit e short circ uit.
Vin Vout
V
R1
R2
TLV431
GND
C1
0.1µF
REF
VR1
Vin Vout
GND
AP1084
REG
V
+= 2R1R
1VV REFOUT
)VV(V REFREGOUT +≥
(All features of the regulator
such as short circuit protection,
thermal shutdown, etc, are
maintained.)
Figure 6. Increasing Output Voltage of a Fixed Linear Regulator
One of the useful applications of the TLV431 is in using it to improve the accuracy and/or extend the range and flexibility of fixed voltage
regulators. In t he circuit in F igure 6 above both the output voltage a nd it s accurac y are entirel y determined by t he TLV431, R1 and R2. However
the rest of the features of the regulator (up to 5A output current, output current limiti ng and thermal shutdown) are all sti l l availabl e.
TLV431
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Applic ation Notes (cont.)
Printed Circuit Board Layout Considerations (cont.)
Vin Vout
V
R1
R2
TLV431
GND
C1
0.1µF
REF
VR1
Vin Vout
GND
AP1117 or AP1084
1.2 V
R3
I
B
+= 2R1R
1VV REFOUT
)VV(V REFREGOUT +≥
B
REGOUTIN I)VV(V
3R −−
=
mA18ImA1.0
B
≤≤
(All features of the regulator
such as short circuit
protection, thermal shutdown,
etc, are maintained.)
Figure 7. Adjustable Linear Voltage Regulator
Figure 7 is simil ar t o Figure 6 with adjustability added. Not e the addition of R3. This is only required f or the A P 1117 due to the fact that its ground
or adjustment pin can only supply a few micro-am ps of current at best. R3 is therefore needed to provide sufficient bias current f or the TLV431.
Ordering Information
Tol. Part Number Package Part Mark Status Reel Si ze Tape Width Quanity per
Reel
1%
TLV431AE5TA SOT25 V1A Active 7”, 180mm 8mm 3000
TLV431AFTA SOT23 V1A Active 7”, 180mm 8mm 3000
TLV431AH6TA SC70-6
(SOT363) V1A Active 7”, 180mm 12mm 1000
0.5%
TLV431BE5TA SOT25 V1B Active 7”, 180mm 8mm 3000
TLV431BFTA SOT23 V1B Active 7”, 180mm 8mm 3000
TLV431BH6TA SC70-6
(SOT363) V1B Active 7”, 180mm 12mm 1000
0.2%
TLV431TFTA SOT23 V1T Active 7”, 180mm 8mm 3000
TLV431
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Package Ou t lin e Dim en sio ns (All dimensions in mm.)
Please see AP02002 at http://www.diodes.c om/datasheets/ap02002.pdf for latest version.
SOT23
SOT25
SC70-6 (SOT363)
SOT23
Dim
Min
Max
Typ
A
0.37
0.51
0.40
B
1.20
1.40
1.30
C
2.30
2.50
2.40
D
0.89
1.03
0.915
F
0.45
0.60
0.535
G
1.78
2.05
1.83
H
2.80
3.00
2.90
J
0.013 0.10 0.05
K
0.903 1.10 1.00
K1
— — 0.400
L
0.45
0.61
0.55
M
0.085
0.18
0.11
α
0° 8° —
All Dimensions in mm
SOT25
Dim
Min
Max
Typ
A
0.35
0.50
0.38
B
1.50 1.70 1.60
C
2.70
3.00
2.80
D
0.95
H
2.90
3.10
3.00
J
0.013
0.10
0.05
K
1.00
1.30
1.10
L
0.35
0.55
0.40
M
0.10
0.20
0.15
N
0.70
0.80
0.75
α
0°
8°
All Dimensions in mm
SC70-6 (SOT363)
Dim
Min
Max
Typ
A
0.10
0.30
0.25
B
1.15
1.35
1.30
C
2.00
2.20
2.10
D
0.65 Typ
F
0.40
0.45
0.425
H
1.80
2.20
2.15
J
0
0.10
0.05
K
0.90
1.00
1.00
L
0.25
0.40
0.30
M
0.10
0.22
0.11
α
0°
8°
-
All Dimensions in mm
A
M
JL
D
F
BC
H
K
G
K1
A
M
JL
D
BC
H
KN
A
M
JL
D
B C
H
K
F
TLV431
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Suggested Pad Layout
Please see AP02001 at http://www.diodes.c om/datasheets/ap02001.pdf for the latest version.
SOT23
SOT25
SC70-6 (SOT363)
Dimensions
Value (in mm)
Z
2.9
X
0.8
Y
0.9
C
2.0
E
1.35
Dimensions
Value (in mm)
Z
3.20
G
1.60
X
0.55
Y
0.80
C1
2.40
C2
0.95
Dimensions
Value (in mm)
Z
2.5
G
1.3
X
0.42
Y
0.6
C1
1.9
C2
0.65
XE
Y
C
Z
X
Z
Y
C1
C2
C2
G
X
Z
Y
C1
C2
C2
G
TLV431
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failure of the life support device or to affect its safety or effectiveness.
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