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LCVT 参数 Datasheet PDF下载

LCVT图片预览
型号: LCVT
PDF下载: 下载PDF文件 查看货源
内容描述: 36V ,2A , 2.8MHz降压型开关稳压器 [36V, 2A, 2.8MHz Step-Down Switching Regulator]
分类和应用: 稳压器开关
文件页数/大小: 24 页 / 327 K
品牌: Linear [ Linear ]
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LT3684  
APPLICATIONS INFORMATION  
Table 2. Capacitor Vendors  
VENDOR  
PHONE  
URL  
PART SERIES  
Ceramic,  
Polymer,  
Tantalum  
Ceramic,  
Tantalum  
Ceramic,  
Polymer,  
Tantalum  
Ceramic  
COMMANDS  
Panasonic  
(714) 373-7366  
www.panasonic.com  
EEF Series  
Kemet  
Sanyo  
(864) 963-6300  
(408) 749-9714  
www.kemet.com  
T494, T495  
POSCAP  
www.sanyovideo.com  
Murata  
AVX  
(408) 436-1300  
(864) 963-6300  
www.murata.com  
www.avxcorp.com  
Ceramic,  
Tantalum  
Ceramic  
TPS Series  
Taiyo Yuden  
www.taiyo-yuden.com  
Table 3. Diode Vendors  
PART NUMBER  
When choosing a capacitor, look carefully through the  
data sheet to find out what the actual capacitance is under  
operating conditions (applied voltage and temperature).  
A physically larger capacitor, or one with a higher voltage  
rating, may be required. High performance tantalum or  
electrolyticcapacitorscanbeusedfortheoutputcapacitor.  
Low ESR is important, so choose one that is intended for  
use in switching regulators. The ESR should be specified  
by the supplier, and should be 0.05Ω or less. Such a  
capacitor will be larger than a ceramic capacitor and will  
have a larger capacitance, because the capacitor must be  
large to achieve low ESR. Table 2 lists several capacitor  
vendors.  
V
I
V AT 1A  
V AT 2A  
R
AVE  
F
F
(V)  
(A)  
(mV)  
(mV)  
On Semicnductor  
MBRM120E  
MBRM140  
20  
40  
1
1
530  
550  
595  
Diodes Inc.  
B120  
20  
30  
20  
30  
40  
1
1
2
2
2
500  
500  
B130  
B220  
500  
500  
500  
B230  
DFLS240L  
International Rectifier  
10BQ030  
20BQ030  
30  
30  
1
2
420  
470  
470  
Frequency Compensation  
Catch Diode  
The LT3684 uses current mode control to regulate the  
output.Thissimplifiesloopcompensation.Inparticular,the  
LT3684 does not require the ESR of the output capacitor  
for stability, so you are free to use ceramic capacitors to  
achieve low output ripple and small circuit size. Frequency  
compensation is provided by the components tied to the  
The catch diode conducts current only during switch off  
time. Average forward current in normal operation can  
be calculated from:  
I
= I  
(V – V )/V  
OUT IN OUT IN  
D(AVG)  
where I  
is the output load current. The only reason to  
OUT  
V pin, as shown in Figure 2. Generally a capacitor (C )  
C
C
consideradiodewithalargercurrentratingthannecessary  
for nominal operation is for the worst-case condition of  
shorted output. The diode current will then increase to the  
typical peak switch current. Peak reverse voltage is equal  
to the regulator input voltage. Use a diode with a reverse  
voltage rating greater than the input voltage. Table 3 lists  
several Schottky diodes and their manufacturers.  
and a resistor (R ) in series to ground are used. In addi-  
C
tion, there may be lower value capacitor in parallel. This  
capacitor (C ) is not part of the loop compensation but  
F
is used to filter noise at the switching frequency, and is  
required only if a phase-lead capacitor is used or if the  
output capacitor has high ESR.  
3684f  
13