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參數(shù)資料
| 型號(hào)： | LP3923TLX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 電源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PBGA30 |
| 封裝： | 3 X 2.50 MM, MICRO SMD-30 |
| 文件頁數(shù)： | 16/32頁 |
| 文件大?。?/td> | 1718K |
| 代理商： | LP3923TLX |
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Suggested Inductors and Their Suppliers (Preliminary and Untested)
Model
Vendor
Dimensions (mm)
DC R(max)
DO3314-222MXC
Coilcraft
3.3 x 3.3 x 1.4
200 m
LPO3310-222MX
Coilcraft
3.3 x 3.3 x 1.0
150 m
ELL5GM2R2N
Panasonic
5.2 x 5.2 x x 1.5
53 m
CDRH2D142R2
Sumida
3.2 x 3.2 x 1.55
94 m
INPUT CAPACITOR SELECTION
A ceramic input capacitor of 10 F is sufficient for most ap-
plications. A larger value may be used for improved input
voltage filtering. Use X7R or X5R type capacitors, do not use
Y5V. The DC bias characteristics of ceramic capacitors must
be considered when selecting case sizes of 0805 or smaller
for use in the application. Smaller case sizes in many cases
exhibit a large drop in capacitance value as the DC bias in-
creases.
The input filter capacitor supplies current to the PFET switch
of the converter in the first half of each cycle and reduces
voltage ripple imposed on the input power source. A ceramic
capacitor’s low ESR provides the best noise filtering of the
input voltage spikes due to this rapidly changing current. Se-
lect an input filter capacitor with a surge current rating suffi-
cient for the power-up surge from the input power source. The
power-up surge current is approximately the capacitor’s value
(F) times the voltage rise rate (V/s).
The input current ripple can be calculated as:
The worst case I
RMS is:
OUTPUT CAPACITOR SELECTION
A 10 F capacitor is recommended for use at the output of the
buck converter. Use X7R or X5R type capacitors; do not use
Y5V. The DC bias characteristics of ceramic capacitors must
be considered when selecting case sizes of 0805 or smaller
for use in the application. Smaller case sizes in many cases
exhibit a large drop in capacitance value as the DC bias in-
creases. DC bias characteristics vary from manufacturer to
manufacturer and dc bias curves should be requested from
them as part of the capacitor selection process.
The output filter capacitor smooths out current flow from the
inductor to the load, helps maintain a steady output voltage
during transient load changes and reduces output voltage
ripple. These capacitors must be selected with sufficient ca-
pacitance and sufficiently low ESR to perform these functions.
The output voltage ripple is caused by the charging and dis-
charging of the output capacitor and also due to its ESR. It
can be calculated as:
Voltage peak to peak ripple due to capacitance =
Voltage peak to peak ripple due to ESR =
V
PP-ESR = IPP*RESR
Voltage peak to peak ripple, root mean squared =
Note that the output ripple is dependent on the inductor cur-
rent ripple and the equivalent series resistance of the output
capacitor (R
ESR). Because these two components are out of
phase the rms value is used. The R
ESR is frequency depen-
dent (as well as temperature dependent); make sure the
frequency of the R
ESR given is the same order of magnitude
as the switching frequency.
Suggested Capacitors And Their Suppliers
Model
Type
Vendor
Voltage Rating
Case Size
10 F (C
IN and COUT)
GRM21BR60J106k
Ceramic, X5R
MURATA
6.3V
0805
JMK212BJ106K
Ceramic, X5R
TAIYO YUDEN
6.3V
0805
C2012X5R0J106K
Ceramic, X5R
TDK
6.3V
0805
23
www.national.com
LP3923
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LP3923TLX-VB | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PBGA30 |
| LP3923TL-VB | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PBGA30 |
| LP3923TLX-VC | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PBGA30 |
| LP3923TL-VI | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PBGA30 |
| LP3946ILD | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP3923TLX/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 |
| LP3923TLX-VB | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Cellular Phone Power Management Unit |
| LP3923TLX-VB/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 |
| LP3923TLX-VC | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Cellular Phone Power Management Unit |
| LP3923TLX-VC/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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