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參數資料
| 型號： | LT3741IUF#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 1070 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封裝： | 4 X 4 MM, LEAD FREE, PLASTIC, MO-220WGGD-1, QFN-20 |
| 文件頁數： | 5/24頁 |
| 文件大?。?/td> | 243K |
| 代理商： | LT3741IUF#PBF |
LT3741
13
3741fb
APPLICATIONS INFORMATION
Programming Inductor Current
The analog voltage at the CTRL1 pin is buffered and
produces a reference voltage, VCTRL, across an internal
resistor. The regulated average inductor current is deter-
mined by:
I
O =
V
CTRL1
30 R
S
where RS is the external sense resistor and IO is the aver-
age inductor current, which is equal to the output current.
Figure 2 shows the maximum output current vs RS. The
maximum power dissipation in the resistor will be:
P
RS =
0.05V
()2
R
S
Table 1 contains several resistors values, the corresponding
maximum current and power dissipation in the sense resis-
tor. Susumu, Panasonic and Vishay offer accurate sense
resistors. Figure 3 shows the power dissipation in RS.
Table 1. Sense Resistor Values
MAXIMUM OUTPUT
CURRENT (A)
RESISTOR, RS (mΩ) POWER DISSIPATION (W)
1
50
0.05
5
10
0.25
10
5
0.5
25
2
1.25
Inductor Selection
Size the inductor to have approximately 30% peak-to-
peak ripple. The overcurrent set point is equal to the
high level regulated current level set by the CTRL1 pin
with an additional 23mV offset between the SENSE+ and
SENSE– pins. The saturation current for the inductor
should be at least 20% higher than the maximum regulated
current. The following equation sizes the inductor for best
performance:
L
=
V
VO –VO
2
0.3 f
S IO VIN
where VOistheoutputvoltage,IOisthemaximumregulated
current in the inductor and fS is the switching frequency.
Using this equation, the inductor will have approximately
15% ripple at maximum regulated current.
Table 2. Recommended Inductor Manufacturers
VENDOR
WEBSITE
Coilcraft
www.coilcraft.com
Sumida
www.sumida.com
Vishay
www.vishay.com
Würth Electronics
www.we-online.com
NEC-Tokin
www.nec-tokin.com
RS (mΩ)
0
POWER
DISSIPATION
(W)
0.2
0.6
0.8
1.0
1.4
2
10
14
3741 F03
0.4
1.2
8
18 20
4
6
12
16
RS (mΩ)
0
MAXIMUM
OUTPUT
CURRENT
(A)
10
20
30
5
15
25
4
8
12
16
3741 F02
20
2
0
6
10
14
18
Figure 2. RS Value Selection for Regulated Output Current
Figure 3. Power Dissipation in RS
Switching MOSFET Selection
When selecting switching MOSFETs, the following
parameters are critical in determining the best devices for
a given application: total gate charge (QG), on-resistance
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| LT3742EUF#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 24-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數:1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LT3742EUF#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 24-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
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