LM2575SX-ADJ National Semiconductor, LM2575SX-ADJ Datasheet - Page 13

• Manufacturer Part Number: LM2575SX-ADJ
• Description: IC,SMPS CONTROLLER,VOLTAGE-MODE,BIPOLAR,SIP,5PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LM2575SX-ADJ

• Rohs Compliant: NO

Given: V
15V) V
Maximum Load Current
LM2575 Series Buck Regulator Design Procedure
output voltages, see the design procedure for the adjustable
overload or shorted output condition. B. The reverse voltage
electrolytic bypass capacitor located close to the regulator is
information, see the inductor section in the Application Hints
version. B. From the inductor value selection guide, identify
rating must be at least 1.2 times greater than the maximum
2. Output Capacitor Selection (C
output voltage. For a 5V regulator, a rating of at least 8V is
withstand a continuous output short, the diode should have
operation at the LM2575 switching frequency (52 kHz) and
voltage rating should be at least 1.5 times greater than the
3. Catch Diode Selection (D1) A. The catch-diode current
Higher voltage electrolytic capacitors generally have lower
for a current rating of 1.15 x I
(approximately 1% of the output voltage) a value between
I
ESR numbers, and for this reason it may be necessary to
1. Inductor Selection (L1) A. Select the correct Inductor
voltages of 3.3V, 5V, 12V or 15V respectively). For other
stable operation and an acceptable output ripple voltage,
a current rating equal to the maximum current limit of the
LM2575. The most stressful condition for this diode is an
LOAD
100 µF and 470 µF is recommended. B. The capacitor’s
select a capacitor rated for a higher voltage than would
appropriate, and a 10V or 15V rating is recommended.
Identify the inductor value from the inductor code, and
dominate pole-pair of the switching regulator loop. For
select an appropriate inductor from the table shown in
manufacturers. The inductor chosen must be rated for
output capacitor together with the inductor defines the
value selection guide from Figures 3, 4, 5, 6 (Output
rating of the diode should be at least 1.25 times the
Figure 9. Part numbers are listed for three inductor
load current. Also, if the power supply design must
the inductance region intersected by V
4. Input Capacitor (C
PROCEDURE (Fixed Output Voltage Versions)
IN
(Max), and note the inductor code for that region. C.
(Max) = Maximum Input Voltage I
OUT
= Regulated Output Voltage (3.3V, 5V, 12V, or
needed for stable operation.
section of this data sheet.
maximum input voltage.
normally be needed.
IN
) An aluminum or tantalum
LOAD
OUT
. For additional inductor
) A. The value of the
LOAD
IN
(Max) and
(Max) =
13
Given: V
1. Inductor Selection (L1) A. Use the selection guide
shown in Figure 4. B. From the selection guide, the
inductance area intersected by the 20V line and 0.8A line is
L330. C. Inductor value required is 330 µH. From the table
in Figure 9, choose AIE 415-0926, Pulse Engineering
PE-52627, or RL1952.
3. Catch Diode Selection (D1) A. For this example, a 1A
current rating is adequate. B. Use a 30V 1N5818 or SR103
Schottky diode, or any of the suggested fast-recovery
diodes shown in Figure 8.
4. Input Capacitor (C
capacitor located near the input and ground pins provides
sufficient bypassing.
2. Output Capacitor Selection (C
to 470 µF standard aluminum electrolytic. B. Capacitor
EXAMPLE (Fixed Output Voltage Versions)
OUT
= 5V V
voltage rating = 20V.
IN
IN
(Max) = 20V I
) A 47 µF, 25V aluminum electrolytic
OUT
LOAD
) A. C
(Max) = 0.8A
OUT
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= 100 µF