- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄384597 > LM3205SD-2 (NATIONAL SEMICONDUCTOR CORP) 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers PDF資料下載
參數(shù)資料
| 型號： | LM3205SD-2 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| 中文描述： | 1.2 A SWITCHING REGULATOR, 2300 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | LLP-10 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大小： | 1285K |
| 代理商： | LM3205SD-2 |
Application Information
(Continued)
The input filter capacitor supplies AC current drawn by the
PFET switch of the LM3205 in the first part of each cycle and
reduces the voltage ripple imposed on the input power
source. The output filter capacitor absorbs the AC inductor
current, helps maintain a steady output voltage during tran-
sient load changes and reduces output voltage ripple. These
capacitors must be selected with sufficient capacitance and
sufficiently low ESR (Equivalent Series Resistance) to per-
form these functions. The ESR of the filter capacitors is
generally a major factor in voltage ripple.
EN PIN CONTROL
Drive the EN pin using the system controller to turn the
LM3205 ON and OFF. Use a comparator, Schmidt trigger or
logic gate to drive the EN pin. Set EN high (
>
1.2V) for
normal operation and low (
<
0.5V) for a 0.01μA (typ.) shut-
down mode.
Set EN low to turn off the LM3205 during power-up and
under voltage conditions when the power supply is less than
the 2.7V minimum operating voltage. The part is out of
regulation when the input voltage is less than 2.7V. The
LM3205 is designed for mobile phones where the system
controller controls operation mode for maximizing battery life
and requirements for small package size outweigh the addi-
tional size required for inclusion of UVLO (Under Voltage
Lock-Out) circuitry.
microSMD PACKAGE ASSEMBLY AND USE
Use of the microSMD package requires specialized board
layout, precision mounting and careful re-flow techniques, as
detailed in National Semiconductor Application Note 1112.
Refer to the section
Surface Mount Technology (SMD) As-
sembly Considerations.
For best results in assembly, align-
ment ordinals on the PC board should be used to facilitate
placement of the device. The pad style used with microSMD
package must be the NSMD (non-solder mask defined) type.
This means that the solder-mask opening is larger than the
pad size. This prevents a lip that otherwise forms if the
solder-mask and pad overlap, from holding the device off the
surface of the board and interfering with mounting. See
Application Note 1112 for specific instructions how to do this.
The 8-Bump package used for LM3205 has 300micron sol-
der balls and requires 10.82mil pads for mounting on the
circuit board. The trace to each pad should enter the pad
with a 90entry angle to prevent debris from being caught in
deep corners. Initially, the trace to each pad should be 7mil
wide, for a section approximately 7mil long, as a thermal
relief. Then each trace should neck up or down to its optimal
width. The important criterion is symmetry. This ensures the
solder bumps on the LM3205 re-flow evenly and that the
device solders level to the board. In particular, special atten-
tion must be paid to the pads for bumps A1, A3 and B3.
Because PGND and PVIN are typically connected to large
copper planes, inadequate thermal relief’s can result in late
or inadequate re-flow of these bumps.
The microSMD package is optimized for the smallest pos-
sible size in applications with red or infrared opaque cases.
Because the microSMD package lacks the plastic encapsu-
lation characteristic of larger devices, it is vulnerable to light.
Backside metallization and/or epoxy coating, along with
front-side shading by the printed circuit board, reduce this
sensitivity. However, the package has exposed die edges. In
particular, microSMD devices are sensitive to light, in the red
and infrared range, shining on the package’s exposed die
edges.
LLP PACKAGE ASSEMBLY AND USE
Use of the LLP package requires specialized board layout,
precision mounting and careful re-flow techniques, as de-
tailed in National Semiconductor Application Note 1187. Re-
fer to the section
Surface Mount Technology (SMT) Assem-
bly Recommendations.
For best results in assembly,
alignment ordinals on the PC board should be used to
facilitate placement of the device and must attach to the
DAP(Die Attach Pad) of the LLP package. The pad style
used with LLP package must be the NSMD (non-solder
mask defined) type. This means that the solder-mask open-
ing is larger than the pad size. This prevents a lip that
otherwise forms if the solder-mask and pad overlap, from
holding the device off the surface of the board and interfering
with mounting. See Application Note 1187 for specific in-
structions how to do this.
L
www.national.com
14
相關PDF資料 |
PDF描述 |
|---|---|
| LM3205SDX-2 | 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| LM3205TL | 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| LM3205TLX | 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| LM325H | Dual Voltage Regulator |
| LM325 | Dual Voltage Regulator |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3205SD-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 |
| LM3205SDX-2 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
| LM3205SDX-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 |
| LM3205TL | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 2.7V to 5.5V 8-Pin uSMD T/R 制造商:Texas Instruments 功能描述:Adj. Step-Down DC-DC Converter,LM3205TL |
| LM3205TL/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 |
發(fā)布緊急采購，3分鐘左右您將得到回復。