參數(shù)資料
型號(hào)： LP3972
廠商： National Semiconductor Corporation
英文描述： Power Management Unit for Advanced Application Processors
中文描述： 電源管理單元的高級(jí)應(yīng)用處理器
文件頁(yè)數(shù)： 58/59頁(yè)
文件大小： 1072K
代理商： LP3972
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 converters can be implemented by fol-
lowing a few simple design rules.
1.
Place the converters, 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. Special care must be given to place the
input filter capacitor very close to the V
IN
and GND pin.
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 converter 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 converter 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 converter 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 converter 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 converter 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. A good approach is to route the
feedback trace on another layer and to have a ground
plane between the top layer and layer on which the
feedback trace is routed. In the same manner for the
adjustable part it is desired to have the feedback divid-
ers on the bottom layer.
Place noise sensitive circuitry, such as radio RF 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.
L
www.national.com
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LP3972_08 制造商:NSC 制造商全稱(chēng):National Semiconductor 功能描述:Power Management Unit for Advanced Application Processors
LP3972SQ-0514/NOPB 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel
LP3972SQ-5810/NOPB 功能描述:監(jiān)控電路 Pwr Mgmt Unit RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類(lèi)型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
LP3972SQ-A413 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel
LP3972SQ-A413/NOPB 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel
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