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參數(shù)資料
| 型號： | LM3671 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | DC/DC變換器 |
| 英文描述： | 2MHz , 600mA Step-Down DC-DC Converter in SOT23-5 |
| 中文描述： | 高達2MHz，600mA降壓型DC - DC轉換器采用SOT23 - 5 |
| 文件頁數(shù)： | 13/16頁 |
| 文件大?。?/td> | 967K |
| 代理商： | LM3671 |
Application Information
LM3671-ADJ configurations for various V
OUT
V
OUT
(V)
R1(k
)
R2 (k
)
0.7
54.9
137
0.8
118
196
0.9
162
200
1.0
200
200
1.1
191
158
1.2
280
200
1.5
360
180
1.6
442
200
1.7
432
180
1.875
523
191
2.5
402
100
3.3
562
100
(Continued)
C1 (pF)
68
33
22
18
18
12
10
8.2
8.2
6.8
8.2
6.8
C2 (pF)
27
none
none
none
none
none
none
none
none
none
none
33
L (μH)
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
C
IN
(μF)
10
10
10
10
10
10
10
10
10
10
10
10
C
OUT
(μF)
22
22
22
22
22
22
22
22
22
22
22
22
INDUCTOR SELECTION
There are two main considerations when choosing an induc-
tor; the inductor should not saturate, and the inductor current
ripple is small enough to achieve the desired output voltage
ripple. Different saturation current rating specs are followed
by different manufacturers so attention must be given to
details. Saturation current ratings are typically specified at
25C so ratings at max ambient temperature of application
should be requested from manufacturer.
There are two methods to choose the inductor saturation
current rating.
Method 1:
The saturation current is greater than the sum of the maxi-
mum load current and the worst case average to peak
inductor current. This can be written as
I
RIPPLE
: average to peak inductor current
I
OUTMAX
: maximum load current (600mA)
V
IN
: maximum input voltage in application
L : min inductor value including worst case tolerances
(30% drop can be considered for method 1)
f : minimum switching frequency (1.6Mhz)
V
OUT
: output voltage
Method 2:
A more conservative and recommended approach is to
choose an inductor that has saturation current rating greater
than the max current limit of 1150mA.
A 2.2 μH inductor with a saturation current rating of at least
1150 mA is recommended for most applications.The induc-
tor’s resistance should be less than 0.3
for good efficiency.
Table 1
lists suggested inductors and suppliers. For low-cost
applications, an unshielded bobbin inductor could be consid-
ered. For noise critical applications, a toroidal or shielded-
bobbin inductor should be used. A good practice is to lay out
the board with overlapping footprints of both types for design
flexibility. This allows substitution of a low-noise shielded
inductor, in the event that noise from low-cost bobbin models
is unacceptable.
INPUT CAPACITOR SELECTION
A ceramic input capacitor of 10 μF, 6.3V is sufficient for most
applications. Place the input capacitor as close as possible
to the V
IN
pin of the device. A larger value may be used for
improved input voltage filtering. Use X7R or X5R types, do
not use Y5V. DC bias characteristics of ceramic capacitors
must be considered when selecting case sizes like 0805 and
0603. The input filter capacitor supplies current to the PFET
switch of the LM3671 in the first half of each cycle and
reduces voltage ripple imposed on the input power source. A
ceramic capacitor’s low ESR provides the best noise filtering
of the input voltage spikes due to this rapidly changing
current. Select a capacitor with sufficient ripple current rat-
ing. The input current ripple can be calculated as:
L
www.national.com
13
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3671_07 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:2MHz, 600mA Step-Down DC-DC Converter |
| LM3671_08 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:2MHz, 600mA Step-Down DC-DC Converter |
| LM3671LC-1.2 | 功能描述:IC REG BUCK SYNC 1.2V 0.6A 6-LLP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:PowerWise® 標準包裝:50 系列:- 類型:升壓（升壓） 輸出類型:可調式 輸出數(shù):1 輸出電壓:5 V ~ 25 V 輸入電壓:2.3 V ~ 5.5 V PWM 型:電流模式 頻率 - 開關:600kHz，1.2MHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 包裝:管件 供應商設備封裝:8-MSOP |
| LM3671LC-1.2/NOPB | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| LM3671LC-1.2/NPAU | 制造商:Texas Instruments 功能描述: |
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