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| 型号： | LTC4252A-2IMS |
| 厂商： | Linear Technology |
| 文件页数： | 17/36页 |
| 文件大小： | 328K |
| 描述： | IC CTRLR HOTSWAP NEG VOLT 10MSOP |
| 标准包装： | 50 |
| 类型： | 热交换控制器 |
| 应用： | 通用 |
| 内部开关： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 10-MSOP |
| 包装： | 管件 |
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LTC4252-1/LTC4252-2
LTC4252A-1/LTC4252A-2
17
425212fe
For more information www.linear.com/LTC4252-1
applicaTions inForMaTion
2.5% or more will eventually trip the circuit breaker and
shut down the LTC4252. Figure 5 shows the circuit breaker
response time in seconds normalized to 1礔 for I
DRN
=
0礎. The asymmetric charging and discharging of C
T
is
a fair gauge of MOSFET heating.
The normalized circuit response time is estimated by
t
C
T
(礔)
=
4
235.8+8"I
DRN
(
)
"D5.8
?/DIV>
?/DIV>
?/DIV>
?/DIV>
(4)
SHUTDOWN COOLING CYCLE
For the LTC4252-1 (latchoff version), TIMER latches high
with a 5.8礎 pull-up after the circuit breaker fault TIMER
reaches 4V . For the LTC4252-2 (automatic retry version),
a shutdown cooling cycle begins if TIMER reaches the
4V threshold. TIMER starts with a 5.8礎 pull-down until
it reaches the 1V threshold. Then, the 5.8礎 pull-up turns
back on until TIMER reaches the 4V threshold. Four 5.8礎
pull-down cycles and three 5.8礎 pull-up cycles occur
between the 1V and 4V thresholds, creating a time interval
given by:
t
SHUTDOWN
=
7"3V"C
T
5.8礎
(5)
At the 1V threshold of the last pull-down cycle, a GATE
ramp-up is attempted.
SOFT-START
Soft-start limits the inrush current profile during GATE
start-up. Unduly long soft-start intervals can exceed the
MOSFETs SOA rating if powering up into an active load.
If SS floats, an internal current source ramps SS from 0V
to 2.2V for the LTC4252 or 0V to 1.4V for the LTC4252A
in about 230祍. Connecting an external capacitor C
SS
from SS to ground modifies the ramp to approximate an
RC response of:
V
SS
(t)HV
SS
" 1e
t
R
SS
" C
SS
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
(6)
An internal resistive divider (95k/5k for the LTC4252 or
47.5k/2.5k for the LTC4252A) scales V
SS
(t) down by 20
times to give the analog current limit threshold:
V
ACL
(t)=
V
SS
(t)
20
V
OS
(7)
This allows the inrush current to be limited to V
ACL
(t)/R
S
.
The offset voltage, V
OS
(10mV), ensures C
SS
is sufficiently
discharged and the ACL amplifier is in current limit before
GATE start-up. SS is pulled low under any of the following
conditions: in UVLO, in an undervoltage condition, in an
overvoltage condition, during the initial timing cycle or
when the circuit breaker fault times out.
GATE
GATE is pulled low to V
EE
under any of the following
conditions: in UVLO, in an undervoltage condition, in an
overvoltage condition, during the initial timing cycle or
when the circuit breaker fault times out. When GATE turns
on, a 58礎 current source charges the MOSFET gate and
any associated external capacitance. V
IN
limits the gate
drive to no more than 14.5V .
Gate-drain capacitance (C
GD
) feedthrough at the first
abrupt application of power can cause a gate-source
voltage sufficient to turn on the MOSFET . A unique circuit
pulls GATE low with practically no usable voltage at V
IN
FAULT DUTY CYCLE (%)
0
20
40
60
80
100
10
1
0.1
0.01
=
4
[(235.8 + 8 " I
DRN
) " D 5.8]
t
C
T
(礔)
I
DRN
= 0礎
Figure 5. Circuit-Breaker Response Time
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4252A-2IMS#PBF | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4252A-2IMS#TR | 功能描述:IC CTRLR HOTSWAP NEG VOLT 10MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4252A-2IMS#TRPBF | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4252A-2IMSPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
| LTC4252A-2IMSTR | 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
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