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參數(shù)資料
| 型號： | LTC4222CG#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO36 |
| 封裝： | 5.30 MM, LEAD FREE, PLASTIC, SSOP-36 |
| 文件頁數(shù)： | 13/32頁 |
| 文件大小： | 280K |
| 代理商： | LTC4222CG#PBF |
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LTC4222
20
4222fa
APPLICATIONS INFORMATION
Selection of the sense resistor, RS, is set by the overcurrent
threshold of 50mV:
R
mV
I
S
MAX
==
50
001
.
Ω
The MOSFET is sized to handle the power dissipation dur-
ing inrush when output capacitor COUT is being charged.
A method to determine power dissipation during inrush
is based on the principle that:
Energy in CL = Energy in Q1
This uses:
Energy in C
CV
mF
L ==
1
2
1
2
033
12
22
(.
)(
)
or 0.024 joules. Calculate the time it takes to charge up
COUT:
t
CV
I
mF
V
A
STARTUP
L
DD INRUSH
INRUSH
==
=
.
033
12
1
4
4ms
The power dissipated in the MOSFET:
P
t
W
DISS
STARTUP
==
Energy in CL
6
TheSOA(safeoperatingarea)curvesofcandidateMOSFETs
must be evaluated to ensure that the heat capacity of the
package tolerates 6W for 4ms. The SOA curves of the
Fairchild FDC653N provide for 2A at 12V (24W) for 10ms,
satisfying this requirement. Since the FDC653N has less
than 8nF of gate capacitance and we are using a GATE
RC network, the short-circuit stability of the current limit
should be checked and improved by adding a capacitor
from GATE to SOURCE if needed.
The inrush current is set to 1A using C1:
C
CI
I
LGATE
INRUSH
1
=
C
mF
μA
A
CnF
1
033
12
1
13 9
==
.
or
The inrush dI/dt is set to 10A/ms using CSS:
C
I
R
μA
SS
SENSE
=
=
dl/dt
A
s
.
.
0 0429
1
10
0 0
0429 1
10000 0 01
43
.
Ω
=
nF choose 4.7nF
For a start-up time of 4ms with a 2x safety margin we
choose:
C
t
C
ms
TIMER
STARTUP
SS
TIMER
=+
=
2
8
12.3ms/μF
12
2.3ms/μF
F
+=
47
2 0 68
.
nF
μ
Note the minimum value of CTIMER is 10nF.
The UV and OV resistor string values can be solved in the
following method. First pick R3 based on ISTRING being
1.235V/R3 at the edge of the OV rising threshold. Then
solve the following equations:
R
V
R
UV
OV
OV OFF
UV ON
TH RISING
TH FALL
23
=
()
(
IING
R
)
–3
R
VR
R
UV
RR
UV ON
TH RISING
1
32
=
+
()
(
)
––
In our case we choose R3 to be 3.4k to give a resistor
string current below 100μA.
Then solving the equations results in R2 = 1.16k and
R1 = 34.6k.
The FB divider is solved by picking R8 and solving for R7,
choosing 3.57k for R8 we get:
R
VR
FB
R
PWRGD UP
TH RISING
7
8
=
()
–
Resulting in R7 = 30k
A 0.1μF capacitor, CF, is placed on the UV pins to prevent
supply glitches from turning off the GATE via UV or OV.
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| LTC4222CG-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Hot Swap Controller with I2C Compatible Monitoring |
| LTC4222CUH#PBF | 功能描述:IC CTRLR DUAL HOT SWAP 32-QFN 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) |
| LTC4222CUH#TRPBF | 功能描述:IC CTRLR DUAL HOT SWAP 32-QFN 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) |
| LTC4222CUH-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Hot Swap Controller with I2C Compatible Monitoring |
| LTC4222CUH-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Hot Swap Controller with I2C Compatible Monitoring |
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