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參數(shù)資料
| 型號： | LM3670 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | RECTIFIER STANDARD SINGLE 1A 100V 100 30A-ifsm 5uA-ir 1V-vf A405 5K/REEL-13 |
| 中文描述： | 微型降壓型DC - DC轉換器的超低電壓電路 |
| 文件頁數(shù)： | 15/17頁 |
| 文件大?。?/td> | 997K |
| 代理商： | LM3670 |
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
IC, resulting in poor regulation or instability.
Good layout for the LM3670 can be implemented by follow-
ing a few simple design rules, as illustrated in .
1.
Place the LM3670 on TBDmil (TBD/1000 in.) pads.
Place the LM3670, inductor and filter capacitors close
together and make the traces 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 within
0.2 in. (5 mm) of the LM3670.
2.
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 LM3670 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 LM3670 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.
3.
Connect the ground pins of the LM3670, 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 LM3670 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 path, away from noisy traces between the power
components.
The voltage feedback trace must remain
close to the LM3670 circuit and should be direct but
should be routed opposite to noisy components. This
reduces EMI radiated onto the DC-DC converter’s own
voltage feedback trace.
Place noise sensitive circuitry, such as radio IF blocks,
away from the DC-DC converter, CMOS digital blocks
and other noisy circuitry.
Interference with noise-
sensitive circuitry in the system can be reduced through
distance.
4.
5.
6.
20075831
FIGURE 6. Board Layout Design Rules for the LM3670
L
www.national.com
15
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3670_06 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits |
| LM3670B-0250 WAF | 制造商:Texas Instruments 功能描述: |
| LM3670MF-1.2 | 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 |
| LM3670MF-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 |
| LM3670MF-1.2/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter IC |
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