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參數(shù)資料
| 型號： | LT4351CMS |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | MOSFETs |
| 英文描述： | JACK RJ45 8POS/2PORT RTANG PCB |
| 中文描述： | 0.67 A BUF OR INV BASED MOSFET DRIVER, PDSO10 |
| 封裝： | PLASTIC, MSOP-10 |
| 文件頁數(shù)： | 8/20頁 |
| 文件大?。?/td> | 270K |
| 代理商： | LT4351CMS |
LT4351
8
sn4351 4351fs
OPERATIOU
Increasingly, system designers have to deal with multiple
supply sources. The multiplicity may provide parallel, re-
dundant supplies for increased reliability or provide a means
of connecting disparate supplies. In all cases the desire is
for behavior like a diode but with no loss or voltage drop.
ORing diodes have been the conventional means of
connecting these supplies. The disadvantage of this ap-
proach is that diodes introduce efficiency loss because of
their forward voltage drop. This variable voltage drop also
degenerates supply tolerance. Additionally, diodes pro-
vide no information concerning the status of the sourcing
supply. Separate control must also be added to ensure
that a supply that is out of range is not allowed to affect
the common supply.
The LT4351 eliminates these problems by using N-channel
MOSFETs as the pass elements. The MOSFET is turned on
when power is being passed, allowing for a low voltage
drop from the supply to the load. When the input source
voltage drops below the output common supply voltage it
turns off the MOSFET, thereby matching the function and
performance of an ideal diode.
The LT4351 drives either a single MOSFET or dual back-
to-back MOSFETs. Dual MOSFETs are chosen to eliminate
current flow from the input supply to the output supply
when the V
IN
voltage is greater than OUT.
A driver amplifier monitors the input (V
IN
) and output
(OUT) and controls the MOSFETs. If V
IN
exceeds OUT by
15mV, GATE goes high and turns on the MOSFET(s)
allowing for power passage.
Undervoltage and overvoltage comparators C
UV
, C
OV
and
C
OVF
also control power passage. A resistive divider in
conjunction with the UV and OV pins sets appropriate
thresholds such that the MOSFET(s) is off when the UV pin
is below 300mV or OV pin is above 300mV.
To help deal with the transients on the supply lines, the UV
input has current hysteresis. When the UV voltage drops
below the 300mV threshold, a 10
μ
A current is pulled from
the pin. Thus the user can set the hysteresis level through
appropriate values in the divider.
Overvoltage shutdown occurs in two stages. The first
occurs when the OV pin exceeds the 300mV reference.
When OV just exceeds the reference, an internal capacitor
starts charging, delaying the signal to turn off the
MOSFET(s).
The second occurs when the OV pin exceeds 330mV. The
OVF comparator will immediately trip pulling GATE to
GND. This affords a delay inversely proportional to the
amount of overdrive. This also provides for glitch immu-
nity without compromising response time in the event of
a serious overvoltage condition.
The FAULT output indicates the status of the C
OV
, C
OVF
and
C
UV
comparators. It pulls low during a fault condition. It
also pulls low when GATE is at compliance and V
IN
> OUT
by more than 0.21V indicating a probable nonfunctioning
MOSFET. Compliance occurs when GATE is at the lesser
of OUT + 7.4V or V
DD
– 2.3V. FAULT derives its drive from
the greater of V
IN
or OUT. It is active if V
IN
or OUT is greater
than 0.9V. If V
IN
or OUT is below this level, the output state
is not guaranteed.
The gate drive consists of a high current, wide bandwidth
amplifier (Driver). When the amplifier is enabled, it at-
tempts to regulate the GATE voltage such that the voltage
across the MOSFET(s) is approximately 15mV. If the
MOSFET(s) on resistance is so high as to prevent regula-
tion, then GATE goes to compliance and the MOSFET(s)
fully turns on. The inputs to the amplifier are V
IN
and OUT.
The GATE pin sources current from V
DD
and sinks current
to GND. The maximum GATE to V
IN
voltage is the lesser of
V
DD
– 2.3V or 7.4V above V
OUT
or V
IN
(internal clamp
voltage).
The STATUS comparator, ST, pulls low when GATE ex-
ceeds V
IN
by 0.7V. This occurs when V
IN
> OUT + 15mV.
The STATUS pin pulls low as an indication that power is
passing through the MOSFET(s).
If V
IN
is greater than OUT by 0.21V and GATE > V
IN
+ 7.4V
or at compliance (GATE = V
DD
– 2.3V), STATUS will go
high as an indication of a likely open MOSFET. FAULT will
pull low in this state indicating the probable fault.
The gate drive amplifier and STATUS function derive
power from V
DD
. The circuit requires V
DD
> 2.5V. If V
DD
is
present, the gate drive amplifier and STATUS are active
independent of the state of V
IN
. If in a fault, GATE pulls
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT4351CMS#PBF | 功能描述:IC CTLR MOSFET DIODE-OR 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - O 圈控制器 系列:- 標準包裝:1,000 系列:- 應用:電池備份，工業(yè)/汽車，大電流開關(guān) FET 型:- 輸出數(shù):5 內(nèi)部開關(guān):是 延遲時間 - 開啟:100ns 延遲時間 - 關(guān)閉:- 電源電壓:3 V ~ 5.5 V 電流 - 電源:250µA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC N 包裝:帶卷 (TR) |
| LT4351CMS#TR | 功能描述:IC CTRLR MOSFET DIODE-OR 10MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - O 圈控制器 系列:- 標準包裝:1,000 系列:- 應用:電池備份，工業(yè)/汽車，大電流開關(guān) FET 型:- 輸出數(shù):5 內(nèi)部開關(guān):是 延遲時間 - 開啟:100ns 延遲時間 - 關(guān)閉:- 電源電壓:3 V ~ 5.5 V 電流 - 電源:250µA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC N 包裝:帶卷 (TR) |
| LT4351CMS#TRPBF | 功能描述:IC CTRLR MOSFET DIODE-OR 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - O 圈控制器 系列:- 標準包裝:1,000 系列:- 應用:電池備份，工業(yè)/汽車，大電流開關(guān) FET 型:- 輸出數(shù):5 內(nèi)部開關(guān):是 延遲時間 - 開啟:100ns 延遲時間 - 關(guān)閉:- 電源電壓:3 V ~ 5.5 V 電流 - 電源:250µA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC N 包裝:帶卷 (TR) |
| LT4351IMS | 功能描述:IC CTRLR MOSFET DIODE-OR 10MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - O 圈控制器 系列:- 標準包裝:1,000 系列:- 應用:電池備份，工業(yè)/汽車，大電流開關(guān) FET 型:- 輸出數(shù):5 內(nèi)部開關(guān):是 延遲時間 - 開啟:100ns 延遲時間 - 關(guān)閉:- 電源電壓:3 V ~ 5.5 V 電流 - 電源:250µA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC N 包裝:帶卷 (TR) |
| LT4351IMS#PBF | 功能描述:IC CTLR MOSFET DIODE-OR 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - O 圈控制器 系列:- 標準包裝:1,000 系列:- 應用:電池備份，工業(yè)/汽車，大電流開關(guān) FET 型:- 輸出數(shù):5 內(nèi)部開關(guān):是 延遲時間 - 開啟:100ns 延遲時間 - 關(guān)閉:- 電源電壓:3 V ~ 5.5 V 電流 - 電源:250µA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC N 包裝:帶卷 (TR) |
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