Datasheet

~
~
P
−
+
P
P
V
CC
V
FB
Current
Sense
Gate Drive
GND
Controller
P
P
P P
TLV431
or
TLV431A
or
TLV431B
V
O
3.3 V
V
I
120 V
TLV431, TLV431A, TLV431B
SLVS139U –JULY 1996–REVISED JANUARY 2014 www.ti.com
APPLICATION INFORMATION
Figure 21 shows the TLV431, TLV431A, or TLV431B used in a 3.3-V isolated flyback supply. Output voltage V
O
can be as low as reference voltage V
REF
(1.24 V ± 1%). The output of the regulator, plus the forward voltage
drop of the optocoupler LED (1.24 + 1.4 = 2.64 V), determine the minimum voltage that can be regulated in an
isolated supply configuration. Regulated voltage as low as 2.7 Vdc is possible in the topology shown in
Figure 21.
Figure 21. Flyback With Isolation Using TLV431, TLV431A, or TLV431B
as Voltage Reference and Error Amplifier
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Product Folder Links :TLV431 TLV431A TLV431B