LM317M
V
O
I
O
V
out
R
1
+25V
LM317M
1.25k
V
in
D
1
Adjust
D1
1N914
1N4002
LM317M
R
2
V
in
V
out
V
in
V
out
500
D2
1N914
* To provide current limiting of I
ꢂto the system ground, the source of
O
+
ꢀ
1.0mF
120
ꢀꢂthe current limiting diode must be tied to
ꢀꢂ a negative voltage below −7.25 V.
Adjust
720
1N5314
MPS2222
1.0k
V
ref
R ≥
2
TTL
Control
I
DSS
V
*
SS
V
ref
R =
1
I + I
Omax DSS
Minimum V = 1.25 V
out
V
O
< P + 1.25 V + V
OV SS
I
− I < I < 500 mA − I
P O P
As shown O < I < 495 mA
Lmin
D protects the device during an input short circuit.
1
O
Figure 21. Adjustable Current Limiter
Figure 22. 5 V Electronic Shutdown Regulator
I
out
R
R
2
1
V
out
V
in
LM317M
V
in
V
out
LM317M
V
out
240
1N4001
I
Adj
Adjust
Adjust
50k
R
2
MPS2907
V
+
1.25 V
^
Adj
R + R
ref
I
=
+ I
outmax
10mF
R + R
1
1
2
2
5.0 mA < I < 100 mA
out
Figure 23. Slow Turn−On Regulator
Figure 24. Current Regulator
100
2.4 280
2.0 240
2.50
1.25
0.83
0.63
0.50
0.42
0.35
P
for T = 50°C
P
for T = 50°C
D(max)
A
D(max) A
Free Air
Mounted
Vertically
Free Air
Mounted
Vertically
90
80
70
60
50
40
2.0 oz. Copper
L
2.0 oz. Copper
L
1.6
200
Minimum
Size Pad
Minimum
Size Pad
1.2 160
0.8 120
L
L
0.4
0
80
40
R
R
q
JA
q
JA
0
5.0
10
15
20
25
30
0
5.0
10
15
20
25
30
L, LENGTH OF COPPER (mm)
L, LENGTH OF COPPER (mm)
Figure 25. DPAK Thermal Resistance and Maximum
Power Dissipation versus PCB Copper Length
Figure 26. SOT−223 Thermal Resistance and Maximum
Power Dissipation versus PCB Copper Length
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