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参数资料
| 型号： | LM22670QMR-5.0 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 5.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | PLASTIC, SOP-8 |
| 文件页数： | 6/20页 |
| 文件大小： | 515K |
| 代理商： | LM22670QMR-5.0 |
30076024
FIGURE 6. Current Flow in a Buck Application
Thermal Considerations
The two highest power dissipating components are the re-
circulating diode and the LM22670 regulator IC. The easiest
method to determine the power dissipation within the
LM22670 is to measure the total conversion losses (Pin –
Pout) then subtract the power losses in the Schottky diode
and output inductor. An approximation for the Schottky diode
loss is:
P = (1 - D) x I
OUT x VD
An approximation for the output inductor power is:
P = I
OUT
2
x R x 1.1,
where R is the DC resistance of the inductor and the 1.1 factor
is an approximation for the AC losses. The regulator has an
exposed thermal pad to aid power dissipation. Adding several
vias under the device to the ground plane will greatly reduce
the regulator junction temperature. Selecting a diode with an
exposed pad will aid the power dissipation of the diode. The
most significant variables that affect the power dissipated by
the LM22670 are the output current, input voltage and oper-
ating frequency. The power dissipated while operating near
the maximum output current and maximum input voltage can
be appreciable. The junction-to-ambient thermal resistance of
the LM22670 will vary with the application. The most signifi-
cant variables are the area of copper in the PC board, the
number of vias under the IC exposed pad and the amount of
forced air cooling provided. The integrity of the solder con-
nection from the IC exposed pad to the PC board is critical.
Excessive voids will greatly diminish the thermal dissipation
capacity. The junction-to-ambient thermal resistance of the
LM22670 TO-263 THIN and PSOP-8 packages are specified
in the Electrical Characteristics table under the applicable
conditions. For more information regarding the TO-263 THIN
package,
refer
to
Application
Note
AN-1797
at
www.national.com.
www.national.com
14
LM22670/LM22670Q
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| LM22670QMRX-5.0 | 5.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM22670QMR-ADJ | 5.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO8 |
| LM22670QTJE-5.0 | 5.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PSSO7 |
| LM22671QMRE-5.0 | 0.9 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO8 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM22670QMR-ADJ | 制造商:NSC 制造商全称:National Semiconductor 功能描述:3A SIMPLE SWITCHER??, Step-Down Voltage Regulator with Synchronization or Adjustable Switching Frequency |
| LM22670QMR-ADJ/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM22670QMRE-5.0/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM22670QMRE-ADJ/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM22670QMRX-5.0/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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