参数资料
| 型号： | LT3502IMS#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/24页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.5A 10MSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 36 V |
| 输入电压： | 3 V ~ 40 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 1.1MHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-MSOP |
LT3502/LT3502A
APPLICATIONS INFORMATION
V SW
20V/DIV
I L
500mA/DIV
V OUT
100mV/DIV
V SW
20V/DIV
I L
500mA/DIV
V OUT
100mV/DIV
1μs/DIV
3502 F02
1μs/DIV
3502 F03
V IN – V OUT
900mA + ? 60ns
V IN = 40V, V OUT = 3.3V
L = 6.8μH, C OUT = 10μF, I OUT = 250mA
Figure 2. Pulse-Skipping Occurs when
Required On-Time is Below 60ns
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
V IN(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:
L
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.
Table 1
V IN = 40V, V OUT = 3.3V
L = 6.8μH, C OUT = 10μF, I OUT = 500mA
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
Inductor Selection and Maximum Output Current
A good first choice for the inductor value is:
L = 1.6(V OUT + V D ) for the LT3502A
L = 4.6(V OUT + V D ) for the LT3502
where V D 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 efficiency 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-
VENDOR
Sumida
Toko
Würth Elektronik
URL
www.sumida.com
www.toko.com
www.we-online.com
PART SERIES
CDRH4D28
CDRH5D28
CDRH8D28
A916CY
D585LC
WE-TPC(M)
WE-PD2(M)
WE-PD(S)
INDUCTANCE RATE (μH)
1.2 to 4.7
2.5 to 10
2.5 to 33
2 to 12
1.1 to 39
1 to 10
2.2 to 22
1 to 27
SIZE (mm)
4.5 × 4.5
5.5 × 5.5
8.3 × 8.3
6.3 × 6.2
8.1 × 8
4.8 × 4.8
5.2 × 5.8
7.3 × 7.3
11
3502fd
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| LT3503EDCB#TRMPBF | 功能描述:IC REG BUCK ADJ 1A 6DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
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