参数资料
型号: LT3502IMS#TRPBF
厂商: Linear Technology
文件页数: 17/24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:
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
or because it is tied to V IN ), then the LT3502/LT3502A’s
internal circuitry will pull its quiescent current through
its SW pin. This is fine if your system can tolerate a few
mA in this state. If you ground the SHDN pin, the SW
pin current will drop to essentially zero. However, if the
V IN pin is grounded while the output is held high, then
parasitic diodes inside the LT3502/LT3502A can pull large
currents from the output through the SW pin and the V IN
pin. Figure 8b shows a circuit that will run only when the
input voltage is present and that protects against a shorted
or reversed input.
Hot Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LT3502/LT3502A circuits. However,
these capacitors can cause problems if the LT3502/LT3502A
are plugged into a live supply (see Linear Technology
Application Note 88 for a complete discussion). The low
loss ceramic capacitor combined with stray inductance in
series with the power source forms an underdamped tank
circuit, and the voltage at the V IN pin of the LT3502/LT3502A
can ring to twice the nominal input voltage, possibly ex-
ceeding the LT3502/LT3502A’s rating and damaging the
part. If the input supply is poorly controlled or the user
will be plugging the LT3502/LT3502A into an energized
supply, the input network should be designed to prevent
this overshoot. Figure 9 shows the waveforms that result
when an LT3502/LT3502A circuit is connected to a 24V
supply through six feet of 24-gauge twisted pair. The first
plot is the response with a 2.2μF ceramic capacitor at the
input. The input voltage rings as high as 35V and the input
current peaks at 20A. One method of damping the tank
circuit is to add another capacitor with a series resistor to
+
LOW
IMPEDANCE
ENERGIZED
24V SUPPLY
+
CLOSING SWITCH
SIMULATES HOT PLUG
I IN
STRAY
INDUCTANCE
DUE TO 6 FEET
(2 METERS) OF
TWISTED PAIR
+
10μF
35V
AI.EI.
V IN
LT3502
2.2μF
LT3502
2.2μF
V IN
20V/DIV
I IN
5A/DIV
(9a)
V IN
20V/DIV
DANGER!
RINGING V IN MAY EXCEED
ABSOLUTE MAXIMUM
RATING OF THE LT3502
20μs/DIV
I IN
5A/DIV
(9b)
20μs/DIV
+
0.1μF
1
LT3502
2.2μF
V IN
20V/DIV
I IN
5A/DIV
(9c)
20μs/DIV
3502 F09
17
Figure 9. A Well Chosen Input Network Prevents Input Voltage Overshoot and
Ensures Reliable Operation When the LT3502 is Connected to a Live Supply
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