参数资料
型号: LM2672M-3.3X
厂商: NATIONAL SEMICONDUCTOR CORP
元件分类: 稳压器
英文描述: 2.2 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDSO8
封装: 0.150 INCH, PLASTIC, SO-8
文件页数: 10/26页
文件大小: 626K
代理商: LM2672M-3.3X
PROCEDURE (Adjustable Output Voltage Version)
EXAMPLE (Adjustable Output Voltage Version)
B.
Select an appropriate capacitor value and voltage rating, using
the capacitor code, from the output capacitor selection table in
Figure 17. There are two solid tantalum (surface mount) capacitor
manufacturers and four electrolytic (through hole) capacitor
manufacturers to choose from. It is recommended that both the
manufacturers and the manufacturer's series that are listed in the
table be used. A table listing the manufacturers' phone numbers is
located in Figure 11.
B.
From the output capacitor selection table in Figure 17, choose
a capacitor value (and voltage rating) that intersects the capacitor
code(s) selected in section A, C20.
The capacitance and voltage rating values corresponding to the
capacitor code C20 are the:
Surface Mount:
33 μF/25V Sprague 594D Series.
33 μF/25V AVX TPS Series.
Through Hole:
33 μF/25V Sanyo OS-CON SC Series.
120 μF/35V Sanyo MV-GX Series.
120 μF/35V Nichicon PL Series.
120 μF/35V Panasonic HFQ Series.
Other manufacturers or other types of capacitors may also be used,
provided the capacitor specifications (especially the 100 kHz ESR)
closely match the characteristics of the capacitors listed in the
output capacitor table. Refer to the capacitor manufacturers' data
sheet for this information.
4. Catch Diode Selection (D1)
A.
In normal operation, the average current of the catch diode is
the load current times the catch diode duty cycle, 1-D (D is the
switch duty cycle, which is approximately V
OUT/VIN). The largest
value of the catch diode average current occurs at the maximum
input voltage (minimum D). For normal operation, the catch diode
current rating must be at least 1.3 times greater than its maximum
average current. However, if the power supply design must
withstand a continuous output short, the diode should have a
current rating greater than the maximum current limit of the
LM2672. The most stressful condition for this diode is a shorted
output condition.
4. Catch Diode Selection (D1)
A.
Refer to the table shown in Figure 12. Schottky diodes provide
the best performance, and in this example a 1A, 40V Schottky diode
would be a good choice. If the circuit must withstand a continuous
shorted output, a higher current (at least 2.2A) Schottky diode is
recommended.
B.
The reverse voltage rating of the diode should be at least 1.25
times the maximum input voltage.
C.
Because of their fast switching speed and low forward voltage
drop, Schottky diodes provide the best performance and efficiency.
The Schottky diode must be located close to the LM2672 using
short leads and short printed circuit traces.
www.national.com
18
LM2672
相关PDF资料
PDF描述
LM2672M-5.0X 2.2 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDSO8
LM2672LD-5.0/NOPB 2.2 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDSO16
LM2672M-ADJX 2.2 A SWITCHING REGULATOR, 275 kHz SWITCHING FREQ-MAX, PDSO8
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LM2672M-5.0/NOPB 功能描述:直流/直流开关转换器 HIGH EFF 1A STEP- DOWN VLTG REG 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
LM2672M-ADJ 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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