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