欢迎访问ic37.com |
会员登录 免费注册
发布采购

LM2594M-ADJ 参数 Datasheet PDF下载

LM2594M-ADJ图片预览
型号: LM2594M-ADJ
PDF下载: 下载PDF文件 查看货源
内容描述: SIMPLE SWITCHER系列电源转换器150千赫0.5A降压稳压器 [SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator]
分类和应用: 转换器稳压器开关式稳压器或控制器电源电路开关式控制器光电二极管PC
文件页数/大小: 28 页 / 742 K
品牌: NSC [ National Semiconductor ]
 浏览型号LM2594M-ADJ的Datasheet PDF文件第9页浏览型号LM2594M-ADJ的Datasheet PDF文件第10页浏览型号LM2594M-ADJ的Datasheet PDF文件第11页浏览型号LM2594M-ADJ的Datasheet PDF文件第12页浏览型号LM2594M-ADJ的Datasheet PDF文件第14页浏览型号LM2594M-ADJ的Datasheet PDF文件第15页浏览型号LM2594M-ADJ的Datasheet PDF文件第16页浏览型号LM2594M-ADJ的Datasheet PDF文件第17页  
LM2594/LM2594HV Series Buck Regulator Design Procedure (Adjustable  
Output) (Continued)  
PROCEDURE (Adjustable Output Voltage Version)  
EXAMPLE (Adjustable Output Voltage Version)  
4. Feedforward Capacitor (CFF  
4. Feedforward Capacitor (CFF) (See Figure 1 )  
)
For output voltages greater than approximately 10V, an addi-  
tional capacitor is required. The compensation capacitor is  
typically between 50 pF and 10 nF, and is wired in parallel  
with the output voltage setting resistor, R2. It provides addi-  
tional stability for high output voltages, low input-output volt-  
ages, and/or very low ESR output capacitors, such as solid  
tantalum capacitors.  
The table shown in Figure 3 contains feed forward capacitor  
values for various output voltages. In this example, a 1 nF  
capacitor is needed.  
This capacitor type can be ceramic, plastic, silver mica, etc.  
(Because of the unstable characteristics of ceramic capaci-  
tors made with Z5U material, they are not recommended.)  
5. Catch Diode Selection (D1)  
5. Catch Diode Selection (D1)  
A. The catch diode current rating must be at least 1.3 times  
greater than the maximum load current. Also, if the power  
supply design must withstand a continuous output short, the  
diode should have a current rating equal to the maximum  
current limit of the LM2594. The most stressful condition for  
this diode is an overload or shorted output condition.  
A. Refer to the table shown in Figure 11. Schottky diodes  
provide the best performance, and in this example a 1A, 40V,  
1N5819 Schottky diode would be a good choice. The 1A di-  
ode rating is more than adequate and will not be over-  
stressed even for a shorted output.  
B. The reverse voltage rating of the diode should be at least  
1.25 times the maximum input voltage.  
C. This diode must be fast (short reverse recovery time) and  
must be located close to the LM2594 using short leads and  
short printed circuit traces. Because of their fast switching  
speed and low forward voltage drop, Schottky diodes provide  
the best performance and efficiency, and should be the first  
choice, especially in low output voltage applications.  
Ultra-fast recovery, or High-Efficiency rectifiers are also a  
good choice, but some types with an abrupt turn-off charac-  
teristic may cause instability or EMl problems. Ultra-fast re-  
covery diodes typically have reverse recovery times of 50 ns  
or less. Rectifiers such as the 1N4001 series are much too  
slow and should not be used.  
13  
www.national.com