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參數(shù)資料
| 型號： | LM3203 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | DC/DC變換器 |
| 英文描述： | Step-Down DC-DC Converter with Bypass Mode for CDMA / WCDMA RF Power Amplifiers |
| 中文描述： | 降壓型DC - DC轉(zhuǎn)換器帶旁路模式的CDMA / WCDMA射頻功率放大器 |
| 文件頁數(shù)： | 14/15頁 |
| 文件大小： | 1360K |
| 代理商： | LM3203 |
Application Information
(Continued)
1.
Place the LM3203 on 10.82 mil pads.As a thermal relief,
connect to each pad with a 7 mil wide, approximately 7
mil long traces, and when incrementally increase each
trace to its optimal width. The important criterion is sym-
metry to ensure the solder bumps on the LM3203 re-flow
evenly (see
Micro SMD Package Assembly and Use
).
Place the LM3203, inductor and filter capacitors close
together and make the trace short. The traces between
these components carry relatively high switching cur-
rents and act as antennas. Following this rule reduces
radiated noise. Place the capacitors and inductor close
to the LM3203. The input capacitor should be placed
right next to the device between PV
IN
and PGND pin.
Arrange the components so that the switching current
loops curl in the same direction. During the first half of
each cycle, current flows from the input filter capacitor,
through the LM3203 and inductor to the output filter
capacitor and back through ground, forming a current
loop. In the second half of each cycle, current is pulled
up from ground, through the LM3203 by the inductor, to
the output filter capacitor and then back through ground,
forming a second current loop. Routing these loops so
the current curls in the same direction, prevents mag-
netic field reversal between the two half-cycles and re-
duces radiated noise.
2.
3.
4.
Connect the ground pins of the LM3203, and filter ca-
pacitors together using generous component side cop-
per fill as a pseudo-ground plane. Then connect this to
the ground-plane (if one is used) with several vias. This
reduces ground plane noise by preventing the switching
currents from circulating through the ground plane. It
also reduces ground bounce at the LM3203 by giving it
a low impedance ground connection.
Use wide traces between the power components and for
power connections to the DC-DC converter circuit. This
reduces voltage errors caused by resistive losses across
the traces.
Route noise sensitive traces, such as the voltage feed-
back trace, away from noisy traces and components.
The voltage feedback trace must remain close to the
LM3203 circuit and should be routed directly from FB pin
to V
at the output capacitor. A good approach is to
route the feedback trace on another layer and to have a
ground plane between the top layer and the layer on
which the feedback trace is routed. This reduces EMI
radiation on to the DC-DC converter’s own voltage feed-
back trace.
It is recommended to connect BYPOUT pin to V
at
the output capacitor using a separate trace, instead of
connecting it directly to the FB pin for better noise
immunity.
5.
6.
7.
L
www.national.com
14
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PDF描述 |
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| LM3203TL | Step-Down DC-DC Converter with Bypass Mode for CDMA / WCDMA RF Power Amplifiers |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3203TL | 制造商:Texas Instruments 功能描述:CONVERTER BUCK 0.5A ADJ POWERWISE |
| LM3203TL/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 安裝風格: 封裝 / 箱體:CPAK |
| LM3203TLEV | 功能描述:電源管理IC開發(fā)工具 LM3203 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM3203TLX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Step-Down DC-DC Converter with Bypass Mode for CDMA / WCDMA RF Power Amplifiers |
| LM3203TLX/J7002328 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
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