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參數資料
| 型號： | LM2598S-12 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩壓器 |
| 英文描述： | SIMPLE SWITCHER Power Converter 150 kHz 1A Step-Down Voltage Regulator, with Features |
| 中文描述： | 2.6 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, PSSO7 |
| 封裝： | TO-263, SMT-7 |
| 文件頁數： | 13/33頁 |
| 文件大小： | 847K |
| 代理商： | LM2598S-12 |
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LM2598 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) = 1A
F = Switching Frequency (Fixed at a nominal 150 kHz).
1. Programming Output Voltage
(Selecting R
1
and R
2
, as
shown in Figure 1)
Use the following formula to select the appropriate resistor
values.
Select a value for R
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 1)
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 = 1V
and V
D
= diode forward voltage drop = 0.5V
2. Inductor Selection (L1)
A.
Calculate the inductor Volt
microsecond constant
(E
T),
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 7
B.
E
T = 34.8 (V
μs)
C.
on the horizontal axis, select the maximum load current.
C.
I
LOAD
(max) = 1A
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).
D.
From the inductor value selection guide shown in Figure 7
the inductance region intersected by the 35 (V
μs) horizon-
tal line and the 1A vertical line is 100 μH, and the inductor
code is L29.
E.
Select an appropriate inductor from the four manufactur-
er’s part numbers listed in Figure 8
E.
From the table in Figure 8 locate line L29, and select an
inductor part number from the list of manufacturers part
numbers.
3. Output Capacitor Selection (C
OUT
)
3. Output Capacitor SeIection (C
OUT
)
A.
In the majority of applications, low ESR electrolytic or solid
tantalum capacitors between 82 μF and 220 μF provide the
best results. This capacitor should be located close to the IC
using short capacitor leads and short copper traces. Do not
use capacitors larger than 220 μF.
For additional informa-
tion, see section on output capacitors in application
information section.
A.
See section on C
OUT
in Application Information section.
L
www.national.com
13
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM2598S-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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2598S12P+ | 制造商:Texas Instruments 功能描述: |
| LM2598S-12P+ | 制造商:Texas Instruments 功能描述:2.6 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, PSSO7 |
| LM2598S-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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| LM2598S-3.3/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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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