LM2574HVM-ADJ National Semiconductor, LM2574HVM-ADJ Datasheet - Page 14
![DC/DC Converter IC](/photos/18/97/189794/3833494_sml.gif)
LM2574HVM-ADJ
Manufacturer Part Number
LM2574HVM-ADJ
Description
DC/DC Converter IC
Manufacturer
National Semiconductor
Datasheet
1.LM2574HVM-ADJ.pdf
(24 pages)
Specifications of LM2574HVM-ADJ
Input Voltage
60V
Output Current
500mA
Output Voltage
57V
No. Of Pins
14
Peak Reflow Compatible (260 C)
No
Supply Voltage Max
60V
Leaded Process Compatible
No
Mounting Type
Surface Mount
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LM2574HVM-ADJ
Manufacturer:
NS
Quantity:
1 210
www.national.com
Given:
V
V
I
F = Switching Frequency (Fixed at 52 kHz)
1. Programming Output Voltage (Selecting R1 and R2, as
shown in Figure 2 )
Use the following formula to select the appropriate resistor
values.
R
cient and stability with time, use 1% metal film resistors)
2. Inductor Selection (L1)
A. Calculate the inductor Volt • microsecond constant,
E • T (V • µs), from the following formula:
B. Use the E • T value from the previous formula and match
it with the E • T number on the vertical axis of the Inductor
Value Selection Guide shown in Figure 8 .
C. On the horizontal axis, select the maximum load current.
D. Identify the inductance region intersected by the E • T
value and the maximum load current value, and note the in-
ductor value for that region.
E. Select an appropriate inductor from the table shown in Fig-
ure 3 . Part numbers are listed for three inductor manufactur-
ers. The inductor chosen must be rated for operation at the
LM2574 switching frequency (52 kHz) and for a current rating
of 1.5 x I
ductor section in the application hints section of this data
sheet.
LM2574 Series Buck Regulator Design Procedure
LOAD
OUT
IN
1
PROCEDURE (Adjustable Output Voltage Versions)
(Max) = Maximum Input Voltage
can be between 1k and 5k. (For best temperature coeffi-
(Max) = Maximum Load Current
= Regulated Output Voltage
LOAD
. For additional inductor information, see the in-
FIGURE 8. LM2574HV-ADJ Inductor Selection Guide
14
Given:
V
V
I
F = 52 kHz
1. Programming Output Voltage (Selecting R1 and R2)
R
2. Inductor Selection (L1)
A. Calculate E • T (V • µs)
B. E • T = 185 V • µs
C. I
D. Inductance Region = 1000
E. Inductor Value = 1000 µH Choose from Pulse Engineer-
ing Part # PE-52631, or Renco Part # RL-1283-1000.
LOAD
OUT
IN
2
(Max) = 40V
= 1k (19.51−1) = 18.51k, closest 1% value is 18.7k
LOAD
EXAMPLE (Adjustable Output Voltage Versions)
(Max) = 0.4A
= 24V
(Max) = 0.4A
DS011394-16
(Continued)