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参数资料
| 型号： | LM2735XMFEVAL |
| 厂商： | National Semiconductor |
| 文件页数： | 16/58页 |
| 文件大小： | 0K |
| 描述： | BOARD DEMO FOR LM2735 SOT23-5 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步升 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 12V |
| 电流 - 输出： | 500mA |
| 输入电压： | 3 ~ 5.5 V |
| 稳压器拓扑结构： | 升压 |
| 频率 - 开关： | 1.6MHz |
| 板类型： | 完全填充 |
| 已供物品： | 板，文档 |
| 已用 IC / 零件： | LM2735 |
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SNVS485F – JUNE 2007 – REVISED APRIL 2013
Below is an example of a good thermal & electrical PCB design. This is very similar to our LM2735
demonstration boards that are obtainable via the Texas Instruments website. The demonstration board consists
of a two layer PCB with a common input and output voltage application. Most of the routing is on the top layer,
with the bottom layer consisting of a large ground plane. The placement of the external components satisfies the
electrical considerations, and the thermal performance has been improved by adding thermal vias and a top layer
“Dog-Bone”.
C IN
FB
EN
V IN
PCB
P GND
L 1
4
3
A GND
5
V IN
2
C IN
SW
6
P GND
1
C OUT
D 1
V O
Figure 26. Example of Proper PCB Layout
Thermal Design
When designing for thermal performance, one must consider many variables:
Ambient Temperature: The surrounding maximum air temperature is fairly explanatory. As the temperature
increases, the junction temperature will increase. This may not be linear though. As the surrounding air
temperature increases, resistances of semiconductors, wires and traces increase. This will decrease the
efficiency of the application, and more power will be converted into heat, and will increase the silicon junction
temperatures further.
Forced Airflow: Forced air can drastically reduce the device junction temperature. Air flow reduces the hot spots
within a design. Warm airflow is often much better than a lower ambient temperature with no airflow.
External Components: Choose components that are efficient, and you can reduce the mutual heating between
devices.
PCB design with thermal performance in mind:
The PCB design is a very important step in the thermal design procedure. The LM2735 is available in three
package options (5 pin SOT-23, 8 pin MSOP-PowerPAD & 6 pin WSON). The options are electrically the same,
but difference between the packages is size and thermal performance. The WSON and MSOP-PowerPAD have
thermal Die Attach Pads (DAP) attached to the bottom of the packages, and are therefore capable of dissipating
more heat than the SOT-23 package. It is important that the customer choose the correct package for the
application. A detailed thermal design procedure has been included in this data sheet. This procedure will help
determine which package is correct, and common applications will be analyzed.
There is one significant thermal PCB layout design consideration that contradicts a proper electrical PCB layout
design consideration. This contradiction is the placement of external components that dissipate heat. The
greatest external heat contributor is the external Schottky diode. It would be nice if you were able to separate by
distance the LM2735 from the Schottky diode, and thereby reducing the mutual heating effect. This will however
create electrical performance issues. It is important to keep the LM2735, the output capacitor, and Schottky
diode physically close to each other (see Figure 26 ). The electrical design considerations outweigh the thermal
considerations. Other factors that influence thermal performance are thermal vias, copper weight, and number of
board layers.
16
Product Folder Links: LM2735
Copyright ? 2007–2013, Texas Instruments Incorporated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2735XMFEVAL/NOPB | 功能描述:电源管理IC开发工具 LM2735XMF EVAL BOARD 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 |
| LM2735XMFX | 制造商:NSC 制造商全称:National Semiconductor 功能描述:520kHz/1.6MHz - Space-Efficient Boost and SEPIC DC-DC Regulator |
| LM2735XMFX/NOPB | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| LM2735XMY | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Up 2.7V to 5.5V 8-Pin MSOP EP T/R 制造商:Texas Instruments 功能描述:SWITCH REG, BOOST, 1.6MHZ, MSOP8 |
| LM2735XMY/NOPB | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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