Datasheet

LM2575, NCV2575
http://onsemi.com
22
Figure 32. Undervoltage Lockout Circuit for
Buck−Boost Converter
R2
15 k
Z1
1N5242B
R1
15 k
Q1
2N3904
R3
68 k
V
th
≈ 13 V
C
in
100 mF
LM2575−5.0
1
35 GNDON/OFF
+V
in
+V
in
V
out
= -5.0 V
NOTE: This picture does not show the complete circuit.
Adjustable Output, Low−Ripple Power Supply
A 1.0 A output current capability power supply that
features an adjustable output voltage is shown in Figure 33.
This regulator delivers 1.0 A into 1.2 V to 35 V output.
The input voltage ranges from roughly 8.0 V to 40 V. In order
to achieve a 10 or more times reduction of output ripple, an
additional L−C filter is included in this circuit.
Figure 33. Adjustable Power Supply with Low Ripple Voltage
D1
1N5819
L1
150 mH
Output
2
4
Feedback
R2
50 k
R1
1.1 k
L2
20 mH
Regulated
Output Voltage
1.2 V to 35 V @1.0 A
Optional Output
Ripple Filter
Unregulated
DC Input
+
C
out
2200 mF
C1
100 mF
C
in
100 mF
/50 V
LM2575−Adj
1
53ON/OFFGND
+V
in
R , THERMAL RESISTANCE
JAθ
JUNCTION‐TO‐AIR ( C/W)°
30
40
50
60
70
80
1.0
1.5
2.0
2.5
3.0
3.5
010203025155.0
L, LENGTH OF COPPER (mm)
Minimum
Size Pad
2.0 oz. Copper
L
L
Free Air
Mounted
Vertically
P
D
, MAXIMUM POWER DISSIPATION (W)
Figure 34. D
2
PAK Thermal Resistance and Maximum
Power Dissipation versus P.C.B. Copper Length
P
D(max)
for T
A
= 50°C
R
q
JA