參數(shù)資料
型號： LM2597M-ADJ
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 穩(wěn)壓器
英文描述： SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator, with Features
中文描述： 1.4 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, PDSO8
封裝： PLASTIC, SOIC-8
文件頁數(shù)： 12/34頁
文件大?。?/td> 900K
代理商： LM2597M-ADJ
LM2597/LM2597HV Series Buck Regulator Design Procedure (Adjustable
Output)
PROCEDURE (Adjustable Output Voltage Version)
EXAMPLE (Adjustable Output Voltage Version)
Given:
V
OUT
= Regulated Output Voltage
V
IN
(max) = Maximum Input Voltage
I
LOAD
(max) = Maximum Load Current
F = Switching Frequency (Fixed at a nominal 150 kHz).
Given:
V
OUT
= 20V
V
IN
(max) = 28V
I
LOAD
(max) = 0.5A
F = Switching Frequency (Fixed at a nominal 150 kHz).
1. Programming Output Voltage
(Selecting R
1
and R
2
, as
shown in Figure 12)
Use the following formula to select the appropriate resistor
values.
Select a value for R
1
between 240
and 1.5 k
. The lower
resistor values minimize noise pickup in the sensitive feed-
back pin. (For the lowest temperature coefficient and the best
stability with time, use 1% metal film resistors.)
1. Programming Output Voltage
(Selecting R
1
and R
2
, as
shown in Figure 12)
Select R
1
to be 1 k
, 1%. Solve for R
2
.
R
2
= 1k (16.26 1) = 15.26k, closest 1% value is 15.4 k
.
R
2
= 15.4 k
.
2. Inductor Selection (L1)
A.
Calculate the inductor Volt microsecond constant E
T
(V
μs), from the following formula:
where V
SAT
= internal switch saturation voltage = 0.9V
and V
D
= diode forward voltage drop = 0.5V
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 6
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. Each region is
identified by an inductance value and an inductor code (LXX).
E.
Select an appropriate inductor from the four manufacturer’s
part numbers listed in Figure 7
2. Inductor Selection (L1)
A.
Calculate the inductor Volt
microsecond constant (E
T),
B.
E
T = 35.2 (V
μs)
C.
I
LOAD
(max) = 0.5A
D.
From the inductor value selection guide shown in Figure 6
the inductance region intersected by the 35 (V
μs) horizontal
line and the 0.5A vertical line is 150 μH, and the inductor code
is L19.
E.
From the table in Figure 7 locate line L19, and select an
inductor part number from the list of manufacturers part num-
bers.
L
www.national.com
12
相關PDF資料
PDF描述
LM2597M-5.0 SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator, with Features
LM2597M-3.3 SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator, with Features
LM2597M-12 SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator, with Features
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相關代理商/技術參數(shù)
參數(shù)描述
LM2597M-ADJ 制造商:Texas Instruments 功能描述:SWITCHING REG 0.5A ADJ SMD 2597
LM2597M-ADJ/NOPB 功能描述:直流/直流開關轉換器 150KHZ 0.5A STEP- DOWN VLTG REG RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
LM2597MX-12 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
LM2597MX-12/NOPB 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
LM2597MX-3.3 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT
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