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| 型号： | LTC4252A-2CMS#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | Negative Voltage Hot Swap Controllers; Package: MSOP; No of Pins: 10; Temperature Range: 0°C to +70°C |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO10 |
| 封装： | LEAD FREE, PLASTIC, MSOP-10 |
| 文件页数： | 8/36页 |
| 文件大小： | 394K |
| 代理商： | LTC4252A-2CMS#TRPBF |
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LTC4252-1/LTC4252-2
LTC4252A-1/LTC4252A-2
16
425212fb
Overvoltage conditions detected by the OV comparator
will also pull GATE low, thereby shutting down the load.
However, it will not reset the circuit breaker TIMER,
PWRGD flag or shutdown cooling timer. Returning the
supply voltage to an acceptable range restarts the GATE
pin if all the interlock conditions except TIMER are met.
Only during the initial timing cycle does an OV condition
reset the TIMER.
DRAIN
Connecting an external resistor, RD, to the dual function
DRAIN pin allows VOUT sensing* without it being damaged
by large voltage transients. Below 5V, negligible pin leak-
age allows a DRAIN low comparator to detect VOUT less
than 2.385V (VDRNL). This condition, together with the
GATE low comparator, sets the PWRGD flag.
If VOUT > VDRNCL, the DRAIN pin is clamped at about
VDRNCL and the current flowing in RD is given by:
I
VV
R
DRN
OUT
DRNCL
D
≈
(1)
This current is scaled up 8 times during a circuit breaker
fault and is added to the nominal 230
A TIMER current.
This accelerates the fault TIMER pull-up when the MOSFET’s
drain-source voltage exceeds VDRNCLandeffectivelyshort-
ens the MOSFET heating duration.
TIMER
The operation of the TIMER pin is somewhat complex as
it handles several key functions. A capacitor CT is used at
TIMER to provide timing for the LTC4252. Four different
charging and discharging modes are available at TIMER:
1) A 5.8
A slow charge; initial timing and shutdown
cooling delay.
2) A (230
A + 8 IDRN) fast charge; circuit breaker delay.
3) A 5.8
A slow discharge; circuit breaker "cool off" and
shutdown cooling.
4) Low impedance switch; resets the TIMER capacitor
after an initial timing delay, in UVLO, in UV and in OV
during initial timing.
For initial start-up, the 5.8
A pull-up is used. The low
impedance switch is turned off and the 5.8
A current
source is enabled when the interlock conditions are met.
CT charges to 4V in a time period given by:
t
VC
A
T
=
4
58
.
(2)
When CT reaches 4V (VTMRH), the low impedance switch
turns on and discharges CT. A GATE start-up cycle begins
and both SS and GATE are released.
CIRCUIT BREAKER TIMER OPERATION
If the SENSE pin detects more than a 50mV drop across
RS, the TIMER pin charges CT with (230A + 8 IDRN). If
CT chargesto4V,theGATEpinpullslowandtheLTC4252-1
latches off while the LTC4252-2 starts a shutdown cooling
cycle. The LTC4252-1 remains latched off until the UV pin
is momentarily pulsed low or TIMER is momentarily
discharged low by an external switch or VIN dips below
UVLO and is then restored. The circuit breaker timeout
period is given by:
t
VC
AI
T
DRN
=
+
4
230
8
(3)
If VOUT < 5V, an internal PMOS device isolates any DRAIN
pin leakage current, making IDRN = 0A in Equation (3). If
VOUT > VDRNCLduring the circuit breaker fault period, the
charging of CT accelerates by 8 IDRN of Equation (1).
Intermittent overloads may exceed the 50mV threshold at
SENSE, but, if their duration is sufficiently short, TIMER
will not reach 4V and the LTC4252 will not shut the external
MOSFET off. To handle this situation, the TIMER dis-
charges CT slowly with a 5.8A pull-down whenever the
SENSE voltage is less than 50mV. Therefore, any intermit-
tent overload with VOUT > 5V and an aggregate duty cycle
APPLICATIO S I FOR ATIO
WU
U
*VOUT as viewed by the MOSFET; i.e., VDS.
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相关代理商/技术参数 |
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|---|---|
| LTC4252A-2IMS | 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#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 |
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