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參數(shù)資料
| 型號： | LT3502AIDC#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.1 A SWITCHING REGULATOR, 2800 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 2 X 2 MM, LEAD FREE, PLASTIC, DFN-8 |
| 文件頁數(shù)： | 3/24頁 |
| 文件大?。?/td> | 386K |
| 代理商： | LT3502AIDC#PBF |
LT3502/LT3502A
11
3502fd
Figure 2. Pulse-Skipping Occurs when
Required On-Time is Below 60ns
VSW
20V/DIV
VOUT
100mV/DIV
1μs/DIV
VIN = 40V, VOUT = 3.3V
L = 6.8μH, COUT = 10μF, IOUT = 250mA
3502 F02
IL
500mA/DIV
APPLICATIONS INFORMATION
Inductor Selection and Maximum Output Current
A good rst choice for the inductor value is:
L = 1.6(VOUT + VD) for the LT3502A
L = 4.6(VOUT + VD) for the LT3502
where VD is the voltage drop of the catch diode (~0.4V) and
L is in μH. With this value there will be no subharmonic
oscillation for applications with 50% or greater duty cycle.
The inductor’s RMS current rating must be greater than the
maximum load current and its saturation current should
be about 30% higher. For robust operation during fault
conditions, the saturation current should be above 1.2A.
To keep efciency high, the series resistance (DCR) should
be less than 0.1Ω. Table 1 lists several vendors and types
that are suitable.
There are several graphs in the Typical Performance
Characteristics section of this data sheet that show the
maximum load current as a function of input voltage and
inductor value for several popular output voltages. Low
inductance may result in discontinuous mode opera-
Figure 3. Pulse-Skipping with Large Load Current Will be
Limited by the DA Valley Current Limit. Notice the Flat Inductor
Valley Current and Reduced Switching Frequency
As the input voltage increases, the inductor current ramps
up quicker, the number of skipped pulses increases and
the output voltage ripple increases. For operation above
VIN(MAX) the only component requirement is that the
components be adequately rated for operation at the
intended voltage levels.
Inductor current may reach current limit when operating
in pulse-skipping mode with small valued inductors. In
this case, the LT3502/LT3502A will periodically reduce its
frequency to keep the inductor valley current to 650mA
(Figure 3). Peak inductor current is therefore peak current
plus minimum switch delay:
900mA + VIN –VOUT
L
60ns
The part is robust enough to survive prolonged operation
under these conditions as long as the peak inductor cur-
rent does not exceed 1.2A. Inductor current saturation
and junction temperature may further limit performance
during this operating regime.
VSW
20V/DIV
VOUT
100mV/DIV
1μs/DIV
VIN = 40V, VOUT = 3.3V
L = 6.8μH, COUT = 10μF, IOUT = 500mA
3502 F03
IL
500mA/DIV
Table 1
VENDOR
URL
PART SERIES
INDUCTANCE RATE (μH)
SIZE (mm)
Sumida
www.sumida.com
CDRH4D28
CDRH5D28
CDRH8D28
1.2 to 4.7
2.5 to 10
2.5 to 33
4.5
× 4.5
5.5
× 5.5
8.3
× 8.3
Toko
www.toko.com
A916CY
D585LC
2 to 12
1.1 to 39
6.3
× 6.2
8.1
× 8
Würth Elektronik
www.we-online.com
WE-TPC(M)
WE-PD2(M)
WE-PD(S)
1 to 10
2.2 to 22
1 to 27
4.8
× 4.8
5.2
× 5.8
7.3
× 7.3
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| LT3502AIMS#PBF | 功能描述:IC REG BUCK ADJ 0.5A 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LT3502AIMS#TRPBF | 功能描述:IC REG BUCK ADJ 0.5A 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
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