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参数资料
| 型号： | LT3487EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST INV ADJ 10DFN |
| 标准包装： | 121 |
| 类型： | 升压（升压），反相 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.23 V ~ 28 V |
| 输入电压： | 2.3 V ~ 16 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 2MHz |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 10-DFN（3x3） |
| 产品目录页面： | 1331 (CN2011-ZH PDF) |
LT3487
APPLICATIO S I FOR ATIO
Choosing a Feedback Node
The positive channel feedback resistor, R1, may be con-
nected to the V POS pin or to the CAP pin (see Figure 5).
Regulating the V POS pin eliminates the output offset result-
ing from the voltage drop across the output disconnect.
However, in the case of a short-circuit fault at the V POS
pin, the LT3487 will switch continuously because the FBP
pin is low. While operating in this open-loop condition, the
rising voltage at the CAP pin is limited only by the current
limit of the output disconnect. Given worst-case parameters
this voltage may reach 18V in a Li-Ion application. Care
must be taken in high V IN applications when regulating
from the V POS pin. When the short-circuit is removed, the
the capacitor voltages fall back into regulation. While this
is harmless to the LT3487, this should be considered in
the context of the external circuitry if short-circuit events
are expected. Regulating the CAP pin ensures that the
voltage on the V POS pin never exceeds the set output volt-
age after a short-circuit event. However, this setup does
not compensate for the voltage drop across the output
disconnect, resulting in an output voltage that is slightly
lower than the voltage set by the feedback resistor. This
voltage drop (V DISC ) can be accounted for when using
the CAP pin as the feedback node by setting the output
voltage according to the following formula (using V DISC
from Figure 4):
V POS pin will bounce up to the voltage on the CAP pin,
potentially exceeding the programmed output voltage until
R 1 =
V POS + V DISC – 1 .23
25 μA
300
250
200
150
100
50
V BAT
The V BAT pin is a new innovation in the LT3487 that allows
output disconnect operation in a wide range of applica-
tions. The V BAT pin allows the part to stay on until CAP is
less than 1.2V above V BAT . This ensures that the positive
bias doesn’t fall before the negative bias discharges. In
some applications it may be useful to power the inductors
from a different source than V IN . In this case, connect
0
0
20 40 60 80
DISCONNECT CURRENT (mA)
100
2400 G31
V BAT to the source powering the inductors to allow proper
operation of the disconnect. For example, in an automotive
system there may already be a buck regulator producing
3.3V from a 12V battery. The LT3487 enables the user
Figure 4. V CE vs I of Output Disconnect
to power V IN from the 3.3V rail, but power the V BAT pin
SWN
V IN
V BAT
SWP
CAP
SWN
V IN
V BAT
SWP
CAP
LT3487
LT3487
DN
FBN
FBP
DN
FBN
FBP
RUN/SS
V POS
V POS
RUN/SS
V POS
V POS
GND
GND
3487 F05
Figure 5. Feedback Connection Using the V POS and CAP Pins
3487f
11
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| LT3489 | 制造商:LINER 制造商全称:Linear Technology 功能描述:2MHz Boost DC/DC Converter with 2.5A Switch and Soft-Start |
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| LT3489EMS8E#PBF | 功能描述:IC REG BOOST ADJ 2.5A 8MSOP 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 |
| LT3489EMS8E#PBF | 制造商:Linear Technology 功能描述:DC-DC CONVERTER BOOST 2MHZ 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BOOST, 2MHZ, MSOP-8 |
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