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| 型号： | LM3674MFX-2.8 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | LM3674 2MHz, 600mA Step-Down DC-DC Converter in SOT 23-5; Package: SOT-23; No of Pins: 5; Qty per Container: 3000; Container: Reel |
| 中文描述： | 1.2 A SWITCHING REGULATOR, 2600 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | SOT-23, 5 PIN |
| 文件页数： | 5/15页 |
| 文件大小： | 1102K |
| 代理商： | LM3674MFX-2.8 |
Application Information (Continued)
OUTPUT CAPACITOR SELECTION
A ceramic output capacitor of 10 F, 6.3V is sufficient for
most applications. Use X7R or X5R types; do not use Y5V.
DC bias characteristics of ceramic capacitors must be con-
sidered when selecting case sizes like 0805 and 0603. 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 minimum output capacitance to guarantee good
performance is 5.75F at 1.8V dc bias including toler-
ances and over ambient temperature range. The output
filter capacitor smoothes 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 capaci-
tance and sufficiently low ESR to perform these functions.
The output voltage ripple is caused by the charging and
discharging of the output capacitor and by the R
ESR and can
be calculated as:
Voltage peak-to-peak ripple due to capacitance can be ex-
pressed as follow:
Voltage peak-to-peak ripple due to ESR =
Because these two components are out of phase the rms
value can be used to get an approximate value of peak-to-
peak ripple.
Voltage peak-to-peak ripple, root mean squared =
Note that the output ripple is dependent on the current ripple
and the equivalent series resistance of the output capacitor
(R
ESR).
The R
ESR is frequency dependent (as well as temperature
dependent); make sure the value used for calculations is at
the switching frequency of the part.
TABLE 3. Suggested Capacitors and Their Suppliers
Model
Type
Vendor
Voltage Rating
Case size inch (mm)
10 F for C
OUT
GRM21BR60J106K
Ceramic, X5R
Murata
6.3V
0805 (2012)
C2012X5R0J106K
Ceramic, X5R
TDK
6.3V
0805 (2012)
JMK212BJ106K
Ceramic, X5R
Taiyo-Yuden
6.3V
0805 (2012)
4.7 F for C
IN
GRM21BR60J475K
Ceramic, X5R
Murata
6.3V
0805 (2012)
JMK212BJ475K
Ceramic, X5R
Taiyo-Yuden
6.3V
0805 (2012)
C2012X5R0J475K
Ceramic, X5R
TDK
6.3V
0805 (2012)
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.
LM3674
www.national.com
13
相关PDF资料 |
PDF描述 |
|---|---|
| LM4132BMFX-2.5/NOPB | LM4132 SOT-23 Precision Low Dropout Voltage Reference; Package: SOT-23; No of Pins: 5; Qty per Container: 3000/Reel |
| LM4132AMF-1.8 | LM4132 SOT-23 Precision Low Dropout Voltage Reference; Package: SOT-23; No of Pins: 5 |
| LM4132AMF-3.0 | LM4132 SOT-23 Precision Low Dropout Voltage Reference; Package: SOT-23; No of Pins: 5 |
| LM4132AMF-3.3 | LM4132 SOT-23 Precision Low Dropout Voltage Reference; Package: SOT-23; No of Pins: 5 |
| LM4132AMFX-1.8 | LM4132 SOT-23 Precision Low Dropout Voltage Reference; Package: SOT-23; No of Pins: 5 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3674MFX-ADJ | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM3674MFX-ADJ/NOPB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM3676 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:2MHz, 600mA Step-Down DC-DC Converter with Mode Control |
| LM3676SD-1.5 | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM3676SD-1.5/NOPB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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