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參數(shù)資料
| 型號： | LTC4244CGN |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Rugged, CompactPCI Bus Hot Swap Controllers |
| 中文描述： | 4-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO20 |
| 封裝： | 0.150 INCH, PLASTIC, SSOP-20 |
| 文件頁數(shù)： | 14/28頁 |
| 文件大?。?/td> | 333K |
| 代理商： | LTC4244CGN |
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14
LTC4244/LTC4244-1
42441f
Once the power-down sequence is complete, the CPCI
card may be removed from the slot. During extraction, the
precharge circuit continues to bias the bus I/O connector
pins at 1V until the long 5V and 3.3V connector pin
connections are broken.
GATE Pin Capacitor Selection
Both the load capacitance and the LTC4244’s GATE pin
capacitor (C1 in Figure 1) affect the ramp rate of the 5V
OUT
and 3.3V
OUT
voltages. The precise relationship can be
expressed as:
dV
or =I
or
=I
OUT
dt
LIMIT(5V)
C
I
LOAD
–
LIMIT(3.3V)
C
I
C
I
GATE
LOAD V
LOAD VOUT
5
(
V
LOAD
VOUT
=
1
5
(3 3
(3 3
–
(
)
)
)
)
(1)
whichever is slowest. The power-up time for any of the
LTC4244’s outputs where the inrush current is constrained
by that supply’s foldback current limit can be approxi-
mated as:
t
C
V
I
I
on VOUT
(
LOAD
OUT
LIMIT VOUT
(
n
LOAD VOUT
(
n
)
)
)
–
n
<
2
(2)
Where nV
OUT
= 5V
OUT
, 3.3V
OUT
, 12V
OUT
or V
EEOUT
. For
example, if C
LOAD
=2000
μ
F, I
LIMIT(5VOUT)
= 6A and
I
LOAD(5VOUT)
= 5A, the 5V
OUT
turn-on time will be less than
20ms.
If the value of C1 is large enough that it alone determines
the output voltage ramp rate, then the magnitude of the
inrush current initially charging the load capacitance is:
I
C
C
I
INRUSH
LOAD
1
GATE
=
(3)
The maximum power-up time for this condition can be
approximated by:
(
(
t
V
V
C MAX
(
1
I
ON
OUT
THMOSFET MAX
,
GATE MIN
<
+
)
(
)
)
)
(4)
where V
TH,MOSFET(MAX)
is the maximum threshold voltage
of the external 5V or 3.3V MOSFET.
In general, the edge rate (dI/dt) at which the back-end 5V
and 3.3V supply currents are turned on can be limited by
increasing the size of C1. Applications that are sensitive to
the edge rate should characterize how varying the size of
C1 reduces dI/dt for the external MOSFET selected for a
particular design.
In the event of a short-circuit or overcurrent condition, the
LTC4244’s GATE pin can be pulled down within 2
μ
s since
a 1k
(R5 in Figure 1) decouples C1 from the gates of the
external MOSFET’s (Q1 and Q2 in Figure 1).
TIMER Pin Capacitor Selection
During a power-up sequence, a 21
μ
A current source is
connected to the TIMER pin and current limit faults are
ignored until the voltage ramps to within 1.6V of 12V
IN
.
This feature allows the part to power up large capacitive
loads using its foldback current limit. The TIMER inhibit
period can be expressed as:
(
12
t
C
V
V
I
TIMER
TIMER
IN
TIMER
TIMER
=
)
–
(5)
The timer period should be set longer than the duration of
any inrush current that exceeds the LTC4244’s foldback
current limit but yet be short enough not to exceed the
maximum, safe operating area of the external 5V and 3.3V
pass transistors in the event of a short circuit (see Design
Example). As a design aid, the TIMER period as a function
of the timing capacitor using standard values from 0.1
μ
F
to 0.82
μ
F is shown in Table 1.
APPLICATIOU
W
U
U
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4244CGN#PBF | 功能描述:IC CTLR HOT SWAP PCI 20-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:119 系列:- 類型:熱交換控制器 應(yīng)用:通用型，PCI Express? 內(nèi)部開關(guān):無 電流限制:- 電源電壓:3.3V，12V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:80-TQFP 供應(yīng)商設(shè)備封裝:80-TQFP（12x12） 包裝:托盤 產(chǎn)品目錄頁面:1423 (CN2011-ZH PDF) |
| LTC4244CGN#TR | 功能描述:IC CTRLR HOT SWAP CPCI 20-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:119 系列:- 類型:熱交換控制器 應(yīng)用:通用型，PCI Express? 內(nèi)部開關(guān):無 電流限制:- 電源電壓:3.3V，12V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:80-TQFP 供應(yīng)商設(shè)備封裝:80-TQFP（12x12） 包裝:托盤 產(chǎn)品目錄頁面:1423 (CN2011-ZH PDF) |
| LTC4244CGN#TRPBF | 功能描述:IC CTRLR HOTSWAP PCI 20-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:119 系列:- 類型:熱交換控制器 應(yīng)用:通用型，PCI Express? 內(nèi)部開關(guān):無 電流限制:- 電源電壓:3.3V，12V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:80-TQFP 供應(yīng)商設(shè)備封裝:80-TQFP（12x12） 包裝:托盤 產(chǎn)品目錄頁面:1423 (CN2011-ZH PDF) |
| LTC4244CGN-1 | 制造商:Linear Technology 功能描述:Hot Swap Controller 13.5V/14.4V/-14.4V 20-Pin SSOP N |
| LTC4244CGN-1#PBF | 功能描述:IC CTRLR HOTSWAP PCI 20-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:119 系列:- 類型:熱交換控制器 應(yīng)用:通用型，PCI Express? 內(nèi)部開關(guān):無 電流限制:- 電源電壓:3.3V，12V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:80-TQFP 供應(yīng)商設(shè)備封裝:80-TQFP（12x12） 包裝:托盤 產(chǎn)品目錄頁面:1423 (CN2011-ZH PDF) |
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