TLV431AE5TA Diodes Zetex, TLV431AE5TA Datasheet - Page 8

• Manufacturer Part Number: TLV431AE5TA
• Description: IC SHUNT REG 1.24V 1% SOT23-5
• Manufacturer: Diodes Zetex

Specifications of TLV431AE5TA

• Reference Type: Shunt, Adjustable
• Voltage - Output: 1.24 ~ 18 V
• Tolerance: ±1%
• Number Of Channels: 1
• Current - Cathode: 55µA
• Current - Output: 15mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Temperature Coefficient: -
• Current - Quiescent: -

Application Information
In a conventional shunt regulator application (Figure 1), an external series resistor (R
voltage, VI
R
sinks or “shunts” to maintain a voltage equal to V
R
its minimum and the load current is at its maximum value. When the supply voltage is at its maximum and I
R
R
voltage, V
The values of R1 and R2 should be large enough so that the current flowing through them is much smaller than the current
through R3 yet not too large that the voltage drop across them caused I
The most frequent application of the TLV431 is in isolated low output voltage power supplies where the regulated output is
galvanically isolated from the controller. As shown in figure 2 the TLV431 drives current, I
which in turn drives the isolated transistor 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 isolated supply is maintained.
Assuming a forward drop of 1.4V across the opto-coupler diode allows output voltages as low as 2.7V to be regulated.
TLV431
Document number: DS32088 Rev. 5 - 2
3
3
3
3
should be large enough so that the current flowing through the TLV431 is less than 15 mA.
should be small enough to supply at least the minimum acceptable I
is determined by the supply voltage, (V
determines the current that flows through the load (I
KA
N
, and the TLV431.
.
I
K
Figure 2. Using the TLV431 as the regulating element in an isolated PSU
Figure 1
I
L
IN
), the load and operating current, (I
REF
across its feedback pin. Since load current and supply voltage may vary,
www.diodes.com
L
) and the TLV431 (I
8 of 14
REF
KMIN
affects the reference accuracy.
to the TLV431 even when the supply voltage is at
V
V
K
OUT
L
KA
I
). The TLV431 will adjust how much current it
and V
F
and I
R
(min)
Diodes Incorporated
=
3
−
V
V
=
K
OUT
A Product Line of
2
where
REF
), and the TLV431’s reverse breakdown
7 .
V
KA
IN
3
L I
>
) is connected between the supply
×
= V
=
−
+
F
R
⎛
⎜ ⎜
⎝
, through the opto-coupler’s LED
V
V
K I
3
1
REF
KA
+
OUT
≥
R
R
V
2
⎛
⎜ ⎜
⎝
1
OUT
1
⎞
⎟ ⎟
⎠
+
15
R
R
(max)
2
1
mA
L
⎞
⎟ ⎟
⎠
is at its minimum,
−
2
© Diodes Incorporated
7 .
TLV431
April 2011