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參數(shù)資料
| 型號： | LM3205SD-2 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| 中文描述： | 1.2 A SWITCHING REGULATOR, 2300 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | LLP-10 |
| 文件頁數(shù)： | 15/18頁 |
| 文件大?。?/td> | 1285K |
| 代理商： | LM3205SD-2 |
Board Layout Considerations
The LM3205 converts higher input voltage to lower output
voltage with high efficiency. This is achieved with an
inductor-based switching topology. During the first half of the
switching cycle, the internal PMOS switch turns on, the input
voltage is applied to the inductor, and the current flows from
P
VDD
line to the output capacitor (C2) through the inductor.
During the second half cycle, the PMOS turns off and the
internal NMOS turns on. The inductor current continues to
flow via the inductor from the device PGND line to the output
capacitor (C2).
Referring to
Figure 4
, the LM3205 has two major current
loops where pulse and ripple current flow. The loop shown in
the left hand side is most important, because pulse current
shown in
Figure 4
flows in this path. The right hand side is
next. The current waveform in this path is triangular, as
shown in
Figure 4
. Pulse current has many high-frequency
components due to fast di/dt. Triangular ripple current also
has wide high-frequency components. Board layout and cir-
cuit pattern design of these two loops are the key factors for
reducing noise radiation and stable operation. Other lines,
such as from battery to C1(+) and C2(+) to load, are almost
DC current, so it is not necessary to take so much care. Only
pattern width (current capability) and DCR drop consider-
ations are needed.
BOARD LAYOUT FLOW (microSMD)
1.
Minimize C1, PV
, and PGND loop. These traces
should be as wide and short as possible. This is most
important.
2.
Minimize L1, C2, SW and PGND loop. These traces also
should be wide and short. This is the second priority.
20158008
FIGURE 4. Current Loop
20158009
FIGURE 5. Evaluation Board Layout for microSMD
L
www.national.com
15
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3205SD-2/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
| LM3205SDX-2 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| LM3205SDX-2/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
| LM3205TL | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 2.7V to 5.5V 8-Pin uSMD T/R 制造商:Texas Instruments 功能描述:Adj. Step-Down DC-DC Converter,LM3205TL |
| LM3205TL/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK |
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