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參數(shù)資料
| 型號： | LM3204TLX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Miniature, Adjustable, Step-Down DC-DC Converter with Bypass Mode for RF Power Amplifiers |
| 中文描述： | 0.94 A SWITCHING REGULATOR, 2200 kHz SWITCHING FREQ-MAX, PBGA10 |
| 封裝： | ROHS COMPLIANT, THIN MICRO SMD, 10 PIN |
| 文件頁數(shù)： | 15/16頁 |
| 文件大?。?/td> | 874K |
| 代理商： | LM3204TLX |
Application Information
(Continued)
BOARD LAYOUT CONSIDERATIONS
PC board layout is an important part of DC-DC converter
design. Poor board layout can disrupt the performance of a
DC-DC converter and surrounding circuitry by contributing to
EMI, ground bounce, and resistive voltage loss in the traces.
These can send erroneous signals to the DC-DC converter,
resulting in poor regulation or instability. Poor layout can also
result in re-flow problems leading to poor solder joints be-
tween the Micro SMD package and board pads. Poor solder
joints can result in erratic or degraded performance. Good
layout for the LM3204 can by implemented by following a
few simple design rules.
1.
Place the LM3204 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 LM3204 re-flow
evenly (see
Micro SMD Package Assembly and Use
).
2.
Place the LM3204, 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 LM3204. The input capacitor should be placed
right next to the device between PV
IN
and PGND pin.
3.
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 LM3204 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 LM3204 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.
Connect the ground pins of the LM3204, 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 LM3204 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
LM3204 circuit and should be routed directly from FB pin
to V
OUT
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.
4.
5.
6.
7.
L
www.national.com
15
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3204TLX/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 |
| LM3205 | 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 |
| LM320-5 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| LM3205_09 | 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 |
| LM3205SD-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 |
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