- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358631 > 3745SN (Linear Technology Corporation) RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS PDF資料下載
參數(shù)資料
| 型號(hào)： | 3745SN |
| 廠商： | Linear Technology Corporation |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 抗輻射高效，5安培開關(guān)穩(wěn)壓器 |
| 文件頁數(shù)： | 10/32頁 |
| 文件大?。?/td> | 309K |
| 代理商： | 3745SN |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁當(dāng)前第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁
10
LT1374
1374fb
APPLICATIO
S I
FOR
ATIO
U
MAXIMUM OUTPUT LOAD CURRENT
Maximum load current for a buck converter is limited by
the maximum switch current rating (I
P
) of the LT1374.
This current rating is 4.5A up to 50% duty cycle (DC),
decreasing to 3.7A at 80% duty cycle. This is shown
graphically in Typical Performance Characteristics and as
shown in the formula below:
I
P
= 4.5A for DC
≤
50%
I
P
= 3.21 + 5.95(DC) – 6.75(DC)
2
for 50% < DC < 90%
DC = Duty cycle = V
OUT
/V
IN
Example: with V
OUT
= 5V, V
IN
= 8V; DC = 5/8 = 0.625, and;
I
SW(MAX)
= 3.21 + 5.95(0.625) – 6.75(0.625)
2
= 4.3A
Current rating decreases with duty cycle because the
LT1374 has internal slope compensation to prevent current
mode subharmonic switching. For more details, read Ap-
plication Note 19. The LT1374 is a little unusual in this regard
because it has nonlinear slope compensation which gives
better compensation with less reduction in current limit.
Maximum load current would be equal to maximum
switch current for an infinitely large inductor but with
finite inductor size, maximum load current is reduced by
one-half peak-to-peak inductor current. The following
formula assumes continuous mode operation, implying
that the term on the right is less than one-half of I
P
.
P
(
W
U
U
I
OUT(MAX)
=
Continuous Mode
For the conditions above and L = 3.3
μ
H,
I
A
OUT MAX
)
=
( )
(
)
0 57
.
( )
=
=
4 3
.
2 3 3 10
.
500 10
8
4 3
.
3 73
.
6
3
At V
IN
= 15V, duty cycle is 33%, so I
P
is just equal to a fixed
4.5A, and I
OUT(MAX)
is equal to:
( )
=
A
4 5
.
5 15 5
(
2 3 3 10
.
500 10
15
4 5 1 3 5
.
6
3
.
)
( )
Note that there is less load current available at the higher
input voltage because inductor ripple current increases.
This is not always the case. Certain combinations of
inductor value and input voltage range may yield lower
available load current at the lowest input voltage due to
reduced peak switch current at high duty cycles. If load
current is close to the maximum available, please check
maximum available current at both input voltage
extremes. To calculate actual peak switch current with a
given set of conditions, use:
(
( )( )( )
For lighter loads where discontinuous operation can be
used, maximum load current is equal to:
I
I
V
V
V
L f V
SW PEAK
OUT
OUT
2
IN
OUT
IN
)
=
+
)
I
OUT(MAX)
=
Discontinuous mode
Example: with L = 1.2
μ
H, V
OUT
= 5V, and V
IN(MAX
) = 15V,
I
A
OUT MAX
)
=
(
)
( )
)
=
4 5
.
500 10
12 10
.
15
2 5 15 5
1 82
.
2
3
6
The main reason for using such a tiny inductor is that it is
physically very small, but keep in mind that peak-to-peak
inductor current will be very high. This will increase output
ripple voltage. If the output capacitor has to be made larger
to reduce ripple voltage, the overall circuit could actually
wind up larger.
CHOOSING THE INDUCTOR AND OUTPUT CAPACITOR
For most applications the output inductor will fall in the
range of 3
μ
H to 20
μ
H. Lower values are chosen to reduce
physical size of the inductor. Higher values allow more
output current because they reduce peak current seen by
the LT1374 switch, which has a 4.5A limit. Higher values
also reduce output ripple voltage, and reduce core loss.
Graphs in the Typical Performance Characteristics section
show maximum output load current versus inductor size
and input voltage. A second graph shows core loss versus
inductor size for various core materials.
I
)
L f V
(
)
( )( )( )
V
V
V
OUT
2
IN
OUT
IN
I
f L V
(
V
V
V
OUT
IN
OUT
( ) ( )( )( )
)
(
)
2
2
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| 374TG | 300mA LDO Linear Regulators with Internal Microprocessor Reset Circuit |
| 3751 | 4700 |
| 376 | DIODE SCHOTTKY DUAL-DUAL SERIES 30V 200mW 0.38V-vf 200mA-IFM 1mA-IF 0.2uA-IR SOT-363 3K/REEL |
| 37LV128-TISN | DIODE ZENER SINGLE 200mW 2.7Vz 5mA-Izt 0.0741 20uA-Ir 1 SOD-323 3K/REEL |
| 37LV128-TL | DIODE ZENER SINGLE 150mW 2.7Vz 5mA-Izt 0.074 20uA-Ir 1 SOD-523 3K/REEL |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 3746 | 功能描述:電纜固定件和配件 PLCC 1500 BLACK NYLON 94V-2 RoHS:否 制造商:Heyco 類型:Cable Grips, Liquid Tight 材料:Nylon 顏色:Black 安裝方法:Cable 最大光束直徑:11.4 mm 抗拉強(qiáng)度: |
| 3746001000 | 制造商:Laird Technologies Inc 功能描述:CSTR,STR,BF,MC/.080x1.130x.075x4.562 |
| 374605 | 制造商:ERNI Electronics 功能描述:Conn Shrouded Header M 94 POS 2.54mm Solder ST Thru-Hole |
| 374612 | 制造商:ERNI Electronics 功能描述:374612 / R/2 48 M ABC VVV 3-00 GA06 / DIN M / Old Part# 424201 |
| 374624B00000G | 制造商:Aavid Thermalloy 功能描述:- Bulk 制造商:Panduit Corp 功能描述: |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。