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參數(shù)資料
| 型號： | LTC4251CS6 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
| 封裝： | 1 MM HEIGHT, PLASTIC, MO-193, TSOT-23, 6 PIN |
| 文件頁數(shù)： | 6/20頁 |
| 文件大?。?/td> | 235K |
| 代理商： | LTC4251CS6 |
LTC4251/LTC4251-1/
LTC4251-2
14
425112fa
W
CURRENT FLOW
FROM LOAD
CURRENT FLOW
TO –48V BACKPLANE
SENSE RESISTOR
TRACK WIDTH W:
0.03" PER AMP
ON 1 OZ COPPER
TO
SENSE
TO
VEE
425112 F06
Figure 6. Making PCB Connections to the Sense Resistor
APPLICATIO S I FOR ATIO
WU
UU
Figure 5. Recommended Compensation
Capacitor CC vs MOSFET CISS
MOSFET CISS (pF)
COMPENSATION
CAPACITOR
C
(nF)
425112 F05
60
50
40
30
20
10
0
2000
4000
6000
8000
IRF530
IRF540
IRF740
IRF3710
MTY100N10E
CT = 330nF in Equation (2). The MOSFET must be selected
based on this criterion. The IRF530S can handle 100V and
3A for 10ms, and is safe to use in this application.
SUMMARY OF DESIGN FLOW
To summarize the design flow, consider the application
shown in Figure 2, which was designed for 50W:
Calculate maximum load current: 50W/36V = 1.4A; allow-
ing 83% converter efficiency, IIN (MAX) = 1.7A.
Calculate RS: from Equation (3) RS = 20m.
Calculate CT: from Equation (7) CT = 150nF (including 1.5X
correction factor).
Calculate TIMER period: from Equation (2) the short-
circuit time-out period is t = 2.6ms.
Calculate maximum short-circuit current: from Equation
(5) maximum short-circuit current could be as high as
120mV/20m
= 6A.
Consult MOSFET SOA curves: the IRF530S can handle 6A
at 72V for 5ms, so it is safe to use in this application.
FREQUENCY COMPENSATION
The LTC4251/LTC4251-1/LTC4251-2 typical frequency
compensation network for the analog current limit loop is
a series RC (10) and CC connected to VEE. Figure 5
depicts the relationship between the compensation ca-
pacitor CC and the MOSFET’s CISS. The line in Figure 5 is
used to select a starting value for CC based upon the
MOSFET’s CISS specification. Optimized values for CC are
shown for several popular MOSFETs. Differences in the
optimized value of CC versus the starting value are small.
Nevertheless, compensation values should be verified by
board level short-circuit testing.
As seen in Figure 4 previously, at the onset of a short-
circuit event, the input supply voltage can ring dramati-
cally owing to series inductance. If this voltage avalanches
the MOSFET, current continues to flow through the MOSFET
to the output. The analog current limit loop cannot control
this current flow and therefore the loop undershoots. This
effect cannot be eliminated by frequency compensation. A
zener diode is required to clamp the input supply voltage
and prevent MOSFET avalanche.
SENSE RESISTOR CONSIDERATIONS
For proper circuit breaker operation, Kelvin-sense PCB
connections between the sense resistor and the VEE and
SENSE pins are strongly recommended. The drawing in
Figure 6 illustrates the correct way of making connections
between the LTC4251/LTC4251-1/LTC4251-2 and the
sense resistor. PCB layout should be balanced and sym-
metrical to minimize wiring errors. In addition, the PCB
layout for the sense resistor should include good thermal
management techniques for optimal sense resistor power
dissipation.
TIMING WAVEFORMS
System Power-Up
Figure 7 details the timing waveforms for a typical power-
up sequence in the case where a board is already installed
in the backplane and system power is applied abruptly. At
time point 1, the supply ramps up, together with UV/OV
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| LTC4251CS6#PBF | 制造商:Linear Technology 功能描述:Hot Swap Controller 1-CH 6-Pin TSOT-23 |
| LTC4251CS6#TR | 功能描述:IC CTRLR HOTSWAP NEGVOLT SOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠(yuǎn)程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| LTC4251CS6#TRM | 功能描述:IC CTRLR HOTSWAP NEGVOLT SOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:100 系列:- 類型:熱插拔開關(guān) 應(yīng)用:通用 內(nèi)部開關(guān):是 電流限制:可調(diào) 電源電壓:9 V ~ 13.2 V 工作溫度:-40°C ~ 150°C 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-TDFN-EP（3x3） 包裝:管件 |
| LTC4251CS6#TRMPBF | 功能描述:IC CTRLR HOTSWAP NEGVOLT SOT23-6 RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠(yuǎn)程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
| LTC4251CS6#TRPBF | 功能描述:IC CTRLR HOTSWAP NEGVOLT SOT23-6 RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標(biāo)準(zhǔn)包裝:50 系列:- 類型:熱交換控制器 應(yīng)用:-48V 遠(yuǎn)程電力系統(tǒng)，AdvancedTCA ? 系統(tǒng)，高可用性 內(nèi)部開關(guān):無 電流限制:可調(diào) 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-MSOP 包裝:管件 |
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