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參數(shù)資料
| 型號(hào)： | 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)： | 17/28頁 |
| 文件大?。?/td> | 333K |
| 代理商： | LTC4244CGN |
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LTC4244/LTC4244-1
42441f
Calculating R
SENSE
Determining the most appropriate value for the sense
resistor first requires knowing the maximum current needed
by the load under worst-case conditions. Two other pa-
rameters affect the value of the sense resistor. First is the
tolerance of the LTC4244’s circuit breaker threshold volt-
age. The LTC4244’s nominal circuit breaker threshold
voltage is V
CB(NOM)
= 52mV; however it exhibits
±
5mV
tolerance over process and temperature. Second is the
tolerance (RTOL) of the sense resistor. Sense resistors are
available in RTOL’s of
±
1%,
±
2% and
±
5% and exhibit
temperature coefficients of resistance (TCR’s) between
±
75ppm/
°
C and
±
100ppm/
°
C. How the sense resistor
changes as a function of temperature depends on the
I
2
R power being dissipated by it. The power rating of the
sense resistor should accommodate steady-state fault
current levels so that the component is not damaged
before the circuit breaker trips.
Table 2 lists I
TRIP(MIN)
and I
TRIP(MAX)
versus some sug-
gested values of R
SENSE
. Table 7 lists manufacturers and
part numbers for these resistor values.
Table 2. I
TRIP
vs R
SENSE
R
SENSE
(1% RTOL)
0.005
0.007
0.011
I
TRIP(MIN)
9.31A
6.6A
4.2A
I
TRIP(MAX)
11.5A
8.2A
5.2A
Output Voltage Monitor
The status of all four output voltages is monitored by the
power good function. In addition, the PCI_RST# signal is
logically combined on-chip with the HEALTHY# signal to
create LOCAL_PCI_RST# (see Table 3). As a result,
LOCAL_PCI_RST# will be pulled low whenever HEALTHY#
is pulled high independent of the state of the PCI_RST#
signal.
If any of the output voltages drop below the power good
threshold for more than 14
μ
s, the PWRGD pin will be
pulled high and the LOCAL_PCI_RST# signal will be
asserted low.
Table 3. LOCAL_PCI_RST# Truth Table
PCI_RST#
LO
LO
HI
HI
HEALTHY#
LO
HI
LO
HI
LOCAL_PCI_RST#
LO
LO
HI
LO
Precharge
The PRECHARGE input and DRIVE output pins are in-
tended for use in generating the 1V precharge voltage that
is used to bias the bus I/O connector pins during board
insertion and extraction. The LTC4244 is also capable of
generating precharge voltages other than 1V. Figure 7
shows a circuit that can be used in applications requiring
a precharge voltage of less than 1V. The circuit in Figure8
can be used for applications that need precharge voltages
greater than 1V.
Precharge resistors are used to connect the 1V bias volt-
age to the I/O lines with minimal disturbance. Figure 1
shows the precharge application circuit for 5V signaling.
The precharge resistor requirements are more stringent
for 3.3V and Universal Hot Swap boards. If the total leak-
age current on the I/O line is less 2
μ
A, then a 50k resistor
can be connected directly from the 1V bias voltage to the
I/O line. However, many ICs connected to the I/O lines can
have leakage currents up to 10
μ
A. For these applications,
a 10k resistor is used but must be disconnected when the
board is seated as determined by the state of the BD_SEL#
signal. Figure 9 shows a precharge circuit that uses a bus
switch to connect the individual 10k precharge resistors to
the LTC4244’s 1V PRECHARGE pin. The electrical connec-
tion is made (bus switches closed) when the voltage on the
BD_SEL# pin of the plug-in card is pulled-up to 5V
IN
,
which occurs just after the long pins have made contact.
The bus switches are electrically disconnected when the
short, BD_SEL# connector pin makes contact and the
APPLICATIOU
W
U
U
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相關(guān)代理商/技術(shù)參數(shù) |
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| 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(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)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(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)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(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)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(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)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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