LM317, NCV317
+25 V
V
in
V
out
LM317
R
1
1.25
D
1
*
I
out
V
in
1N4002
V
out
LM317
120
Adjust
MPS2222
720
2N5640
1.0 k
TTL
Control
+
1.0
mF
Adjust
R
2
100
D
1
1N4001
D
2
1N4001
* To provide current limiting of I
O
to the system
*
ground, the source of the FET must be tied to a
*
negative voltage below − 1.25 V.
R
1
=
V
ref
I
Omax
+ I
DSS
R
2
≤
V
ref
I
DDS
V
SS
*
Minimum V
out
= 1.25 V
* D
1
protects the device during an input short circuit.
V
O
< BV
DSS
+ 1.25 V + V
SS
,
I
Lmin
− I
DSS
< I
O
< 1.5 A.
As shown 0 < I
O
< 1.0 A.
Figure 23. Adjustable Current Limiter
Figure 24. 5.0 V Electronic Shutdown Regulator
V
in
LM317
V
out
240
1N4001
50 k
MPS2907
+
V
in
LM317
V
out
R
1
I
out
Adjust
R
2
Adjust
I out
+
I
Adj
ref
)
I
Adj
R1
+
1.25 V
R1
10 mA
≤
I
out
≤
1.5 A
V
10
mF
Figure 25. Slow Turn−On Regulator
Figure 26. Current Regulator
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