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參數(shù)資料
| 型號： | LTC4244IGN-1 |
| 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)： | 23/28頁 |
| 文件大?。?/td> | 333K |
| 代理商： | LTC4244IGN-1 |
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23
LTC4244/LTC4244-1
42441f
the PC board. For 1 ounce copper foil plating, a general rule
is 1 ampere of DC current per via making sure the via is
properly dimensioned so that solder completely fills the
void. For other plating thicknesses, check with your PCB
fabrication facility.
Design Example
As a design example, consider a CPCI Hot Swap applica-
tion with the following power supply requirements:
Table 4. Design Example Power Supply Requirements
VOLTAGE
MAXIMUM DC
SUPPLY
SUPPLY CURRENT
12V
5V
3.3V
–12V
LOAD
CAPACITANCE
100
μ
F
2200
μ
F
2200
μ
F
100
μ
F
450mA
5A
7A
100mA
The first step is to select the appropriate values of R
SENSE
for the 5V and 3.3V supplies. Calculating the value of
R
SENSE
is based on I
LOAD(MAX)
and the lower limit for the
circuit breaker threshold voltage (47mV for both the 5V
and 3.3V circuit breakers). If a 1% tolerance is assumed
for the sense resistors, then 5m
and 7m
resistor
values yield the following minimum and maximum I
TRIP
values:
Table 5. I
TRIP
vs R
SENSE
R
SENSE
(1% RTOL)
5m
7m
I
TRIP(MIN)
9.3A
6.6A
I
TRIP(MAX)
11.5A
8.2A
So sense resistor values of 7m
and 5m
should suffice
for the 5V and 3.3V supplies, respectively.
The second step is to select MOSFETs for the 5V and 3.3V
supplies. The IRF7457’s on resistance is less than 10.5m
for V
GS
> 4.5V and a junction temperature of 25
°
C. Since
the maximum load current requirement for the 3.3V sup-
ply is 7A, the steady-state power the device may be
required to dissipate is 514mW. The IRF7457 has a
junction-to-ambient thermal resistance of 50
°
C/Watt. If a
maximum ambient temperature of 50
°
C is assumed, this
yields a junction temperature of 75.7
°
C. According to the
IRF7457’s Normalized On-Resistance vs Junction Tem-
perature curve, the device’s on-resistance can be expected
to increase by about 20% over its room temperature value.
Recalculation of the steady-state values of R
ON
and junc-
tion temperature yields approximately 12.6m
and 81
°
C,
respectively. The I R drop across the 3.3V sense resistor
and series MOSFET at maximum load current under these
conditions will be less than 124mV.
The next step is to select appropriate values for C1
and
C
TIMER
. Assuming that the total current for the 5V supply
is constrained to less than 6A during power-up (6
×
5V
medium length connector pins at 1A per pin), then the
inrush current shouldn’t exceed:
I
INRUSH
< 6A – I
LOAD(5VOUT)
= 6A – 5A = 1A
This yields:
(12)
C
I
F
I
C
A
F
A
nF
GATE MAX
(
INRUSHMAX
2200
1
1
2200
1
100
220
>
μ
>
μ
μ
=
)
(
)
(13)
Hence a C1 value of 330nF
±
10% should suffice. The value
of C
TIMER
for this design example will be constrained by
the duration of the 12V supply inrush current, which
according to Equation 2 is:
t
C
V
I
I
12
t
F
450
V
mA
mA
ms
ON
VOUT
LOAD
)
–
μ
LIMIT MIN
2 100
550
LOAD MAX
ON
VOUT
(
)
(
(
)
(
)
–
12
12
2
12
24
<
<
=
(14)
In order to guarantee that the LTC4244’s TIMER fault
inhibit period is greater than 24ms, the value of C
TIMER
should be:
C
ms I
V
ms
V
12
V
26
–1 9
C
A
V
nF
TIMER
TIMER MAX
TIMER MAX
μ
TIMER
>
>
=
24
12
24
61 8
–
.
(
)
(
)
(15)
So a value of 82nF (
±
10%) should suffice.
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 |
|---|---|
| LTC4244IGN-1#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) |
| LTC4244IGN-1#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) |
| LTC4244IGN-1#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) |
| LTC4244IGNTR | 制造商:Linear Technology 功能描述: |
| LTC4245 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Supply Hot Swap Controller for Advanced Mezzanine Card |
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