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參數(shù)資料
| 型號(hào)： | LM26480SQ-BF/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.4 A SWITCHING REGULATOR, 2400 kHz SWITCHING FREQ-MAX, QCC24 |
| 封裝： | 4 X 4 MM, 0.80 MM HEIGHT, LLP-24 |
| 文件頁數(shù)： | 20/30頁 |
| 文件大?。?/td> | 2447K |
| 代理商： | LM26480SQ-BF/NOPB |
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Board Layout Considerations
PC board layout is an important part of DC-DC converter de-
sign. 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 ii the traces. These
can send erroneous signals to the DC-DC converter IC, re-
sulting in poor regulation or instability. Poor layout can also
result in re-flow problems leading to poor solder joints, which
can result in erratic or degraded performance.
Good layout for the LM26480 bucks can be implemented by
following a few simple design rules, as illustrated in Figure
3.
30040468
FIGURE 3. Board Layout Design Rules for the LM26480
1.
Place the buck inductor and filter capacitors close
together and make the trace short. The traces between
these components carry relatively high switching
currents and act as antennas. Following this rule reduces
radiated noise. Place the capacitors and inductor close
to the buck.
2.
Arrange the components so that the switching current
loops curl in the same direction. During the first halt of
each cycle, current flows from the input filter capacitor,
through the buck 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 buck 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 magnetic
field reversal between the two half-cycles and reduces
radiated noise.
3.
Connect the ground pins of the buck, and filter capacitors
together using generous component-side copper 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 buck by giving it a low-
impedance ground connection.
4.
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
5.
Rout noise sensitive traces, such as the voltage
feedback path, away from noisy traces between the
power components. The voltage feedback trace must
remain close to the buck circuit and should be routed
directly from FB to VOUT at the output capacitor and
should be routed opposite to noise components. This
reduces EMI radiated onto the DC-DC converter’s own
voltage feedback trace.
In mobile phones, for example, a common practice is to place
the DC-DC converter on one corner of the board, arrange the
CMOS digital circuitry around it (since this also generates
noise), and then place sensitive preamplifiers and IF stages
on the diagonally opposing corner. Often, the sensitive cir-
cuitry is shielded with a metal pan and power to it is post-
regulated to reduce conducted noise, using low-dropout
linear regulators.
27
www.national.com
LM26480
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM26480SQX-BF/NOPB | 2.4 A SWITCHING REGULATOR, 2400 kHz SWITCHING FREQ-MAX, QCC24 |
| LM2661M/NOPB | SWITCHED CAPACITOR CONVERTER, 80 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM2660MMX/NOPB | SWITCHED CAPACITOR CONVERTER, 40 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM2661MM/NOPB | SWITCHED CAPACITOR CONVERTER, 80 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM2661MMX/NOPB | SWITCHED CAPACITOR CONVERTER, 80 kHz SWITCHING FREQ-MAX, PDSO8 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM26480SQX-AA | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Externally Programmable Dual High-Current Step-Down DC/DC and Dual Linear Regulators |
| LM26480SQX-AA/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 |
| LM26480SQX-BF | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Externally Programmable Dual High-Current Step-Down DC/DC and Dual Linear Regulators |
| LM26480SQX-BF/NOPB | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Externally Pgrm Dual Hi-Current SD DC/DC RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM26484 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Power Management Unit |
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