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參數資料
| 型號： | LM2598 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | SIMPLE SWITCHER Power Converter 150 kHz 1A Step-Down Voltage Regulator, with Features |
| 中文描述： | SIMPLE SWITCHER系列電源轉換器150千赫1A步降穩壓器的功能， |
| 文件頁數： | 12/33頁 |
| 文件大小： | 847K |
| 代理商： | LM2598 |
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LM2598 Series Buck Regulator Design Procedure (Fixed Output)
(Continued)
PROCEDURE (Fixed Output Voltage Version)
EXAMPLE (Fixed Output Voltage Version)
4. Input Capacitor (C
IN
)
Alow ESR aluminum or tantalum bypass capacitor is needed
between the input pin and ground to prevent large voltage
transients from appearing at the input. In addition, the RMS
current rating of the input capacitor should be selected to be
at least
1
2
the DC load current. The capacitor manufacturers
data sheet must be checked to assure that this current rating
is not exceeded. The curve shown in Figure 16shows typical
RMS current ratings for several different aluminum electro-
lytic capacitor values.
This capacitor should be located close to the IC using short
leads and the voltage rating should be approximately 1.5
times the maximum input voltage.
If solid tantalum input capacitors are used, it is recomended
that they be surge current tested by the manufacturer.
Use caution when using ceramic capacitors for input bypass-
ing, because it may cause severe ringing at the V
IN
pin.
For additional information, see section on input capaci-
tors in Application Information section.
4. Input Capacitor (C
IN
)
The important parameters for the Input capacitor are the
input voltage rating and the RMS current rating. With a
nominal input voltage of 12V, an aluminum electrolytic ca-
pacitor with a voltage rating greater than 18V (1.5 x V
)
would be needed. The next higher capacitor voltage rating is
25V.
The RMS current rating requirement for the input capacitor in
a buck regulator is approximately
1
2
the DC load current. In
this example, with a 1A load, a capacitor with a RMS current
rating of at least 500 mA is needed. The curves shown in
Figure 16 can be used to select an appropriate input capaci-
tor. From the curves, locate the 25V line and note which
capacitor values have RMS current ratings greater than 500
mA. Either a 180 μF or 220 μF, 25V capacitor could be used.
For a through hole design, a 220 μF/25V electrolytic capaci-
tor (Panasonic HFQ series or Nichicon PL series or equiva-
lent) would be adequate. other types or other manufacturers
capacitors can be used provided the RMS ripple current
ratings are adequate.
For surface mount designs, solid tantalum capacitors are
recommended. The TPS series available from AVX, and the
593D series from Sprague are both surge current tested.
Conditions
Inductor
Output Capacitor
Through Hole Electrolytic
Panasonic
HFQ Series
(μF/V)
330/16
270/25
220/25
180/35
220/25
150/35
150/35
330/16
220/25
180/35
180/35
180/16
120/25
100/25
220/25
180/35
82/25
82/25
180/25
82/25
56/25
Surface Mount Tantalum
AVX TPS
Series
(μF/V)
220/10
220/10
220/10
220/10
220/16
100/16
100/16
220/10
220/10
220/10
100/16
220/10
100/16
68/20
68/20
68/20
68/20
68/20
68/20
68/20
68/20
Output
Voltage
(V)
3.3
Load
Current
(A)
1
Max Input
Voltage
(V)
5
7
10
40
6
10
40
8
10
15
40
9
20
40
15
18
30
40
15
20
40
Inductance
(μH)
Inductor
(
#
)
Nichicon
PL Series
(μF/V)
330/16
270/25
220/35
220/35
220/16
150/25
82/35
330/16
220/25
180/35
120/35
180/16
120/25
100/25
220/25
120/25
82/25
82/25
180/25
82/25
56/25
Sprague
595D Series
(μF/V)
330/10
270/10
220/10
180/10
220/10
150/16
100/20
270/10
220/10
150/16
120/16
150/16
100/20
68/25
120/20
120/20
100/20
68/25
120/20
100/20
68/25
22
33
47
68
47
68
100
33
47
68
100
68
150
150
47
68
150
220
68
150
330
L24
L23
L31
L30
L13
L21
L20
L28
L31
L30
L29
L21
L19
L19
L31
L30
L36
L35
L21
L19
L26
0.5
5
1
0.5
12
1
0.5
FIGURE 2. LM2598 Fixed Voltage Quick Design Component Selection Table
L
www.national.com
12
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參數描述 |
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| LM2598S-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 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| 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: |
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| 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 |
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