Datasheet
TL431
R
S
0.1%
I
O
V
I(BATT)
I
O
V
ref
R
S
=
TL431
I
O
R
CL
0.1%
R1
V
I(BATT)
I
out
V
ref
R
CL
I
KA
R1
V
I
(
BATT
)
I
O
h
FE
I
KA
+
+
=
=
TL431
650 Ω
2 kΩ
C
On
Off
R
12 V
n
ref
12 V
Delay = R × C × I
12 V – V
æ ö
ç ÷
ç ÷
è ø
TL431
V
I(BATT)
R3
(see Note A)
R1A
R4
(see Note A)
R2BR2A
R1B
Low Limit = 1 +
R1B
R2B
V
ref
High Limit = 1 +
R1A
R2A
V
ref
LED on When Low Limit < V
I(BATT)
< High Limit
TL431, TL431A, TL431B
TL432, TL432A, TL432B
www.ti.com
SLVS543M –AUGUST 2004–REVISED JULY 2012
A. Select R3 and R4 to provide the desired LED intensity and cathode current ≥1 mA to the TL431 at the available
V
I(BATT)
.
Figure 29. Voltage Monitor
Figure 30. Delay Timer
Figure 31. Precision Current Limiter
Figure 32. Precision Constant-Current Sink
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Product Folder Link(s): TL431 TL431A TL431B TL432 TL432A TL432B