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参数资料
| 型号： | SP6648LEDEB |
| 厂商： | Exar Corporation |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP6648LED |
| 标准包装： | 1 |
| 系列： | * |
APPLICATIONS INFORMATION
Circuit Layout
Printed circuit board layout is a critical part of a
power supply design. Poor designs can result in
excessive EMI on the feedback paths and on the
ground planes with applications involving high
switching frequencies and large peak currents.
Excessive EMI can result in instability or regu-
lation errors. All power components should be
placed on the PC board as closely as possible
with the traces kept short, direct, and wide
(>50mils or 1.25mm). Extra copper on the PC
board should be integrated into ground as a
pseudo-ground plane. On a multilayer PC board,
route the star ground using component-side cop-
per fill, then connect it to the internal ground
plane using vias. For the SP6648 devices, the
inductor and input- and output-filter capacitors
should be soldered with their ground pins as
close together as possible in a star-ground con-
figuration. The V OUT pin must be bypassed di-
rectly to ground as close to the SP6648 devices
as possible (within 0.2in or 5mm). The DC-DC
converter and any digital circuitry should be
placed on the opposite corner of the PC board as
far away from sensitive RF and analog input
stages. Noisy traces, such as from the LX pin,
should be kept away from the voltage-feedback
V OUT node and separated from it using grounded
copper to minimize EMI. See the SP6648EB
Evaluation Board Manual for PC Board Layout
design details.
Component Selection
Selection of capacitors for SP6648 power sup-
ply circuits can be made through the use of the
Component Selection Table. Capacitor equiva-
lent series resistance (ESR) in the range of 0.2 Ω
to 0.3 Ω is a requirement for obtaining sufficient
output voltage ripple for the SP6648 to properly
regulate under load. For ESR values in this
range, low ESR tantalum capacitors are recom-
mended. For example, in the SP6648 applica-
tion circuit a 47 μ F, 10V, low-ESR, surface-
mount tantalum output filter capacitor typically
provides 50mV output ripple when stepping up
from 2.6V to 3.3V at 200mA. Ceramic capaci-
tors have ESR too low to produce enough output
ripple for the SP6648 to regulate the output.
Designers should select input and output ca-
pacitors with a rating exceeding the inductor
current ripple, which is typically set by the
inductor value and the K ON value as given in the
following relationship:
I L(RIPPLE) = K ON /L
For the example of the 10 μ H inductor the induc-
tor current ripple would be 330mA, while for the
22 μ H inductor the inductor current ripple value
would be 150mA. Do not allow tantalum ca-
pacitors to exceed their ripple-current ratings.
An input filter capacitor can reduce peak cur-
rents drawn from the battery and improve effi-
ciency. For most applications, use the same
47 μ F tantalum capacitor as used for the input.
Low-ESR aluminum electrolytic capacitors are
acceptable, provided they meet the ESR re-
quirement of 0.2 Ω to 0.3 Ω , and we list an
appropriate 100 μ F aluminum electrolytic in the
component selection table, but standard alumi-
num electrolytic capacitors are not recom-
mended.
In selecting an inductor, the saturation current
specified for the inductor needs to be greater
than the SP6648 peak current to avoid saturating
the inductor, which would result in a loss in
efficiency and could damage the inductor. The
SP6648 evaluation board uses a Sumida
CDRH5D28 10 μ H inductor with an I SAT value
of 1.3A and a DCR of 0.065 Ω , which easily
handles the I PEAK of 0.85A of the SP6648 and
will deliver high efficiencies. Other inductors
could be selected provided their I SAT is greater
than the I PEAK of the SP6648.
Date: 6/7/06 Rev B
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
9
? 2006 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP6648UEB | 功能描述:电源管理IC开发工具 Ultra Low Quies Cur Hi-Eff Boost Reg RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| SP6649 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP6649EU | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP6649EU/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Ultra-low Quiescent Current, High Efficiency Boost DC-DC Regulator |
| SP664P7FC9086 | 制造商:Thomas & Betts 功能描述:Flush Service Floor Boxes |
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