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| 型号： | LTC4252-2CMS8#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | Negative Voltage Hot Swap Controllers; Package: MSOP; No of Pins: 8; Temperature Range: 0°C to +70°C |
| 中文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封装： | LEAD FREE, PLASTIC, MSOP-8 |
| 文件页数： | 14/36页 |
| 文件大小： | 336K |
| 代理商： | LTC4252-2CMS8#TRPBF |
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LTC4252-1/LTC4252-2
LTC4252A-1/LTC4252A-2
21
425212fc
APPLICATIONS INFORMATION
As seen in Figure 6 previously, at the onset of a short-
circuit event, the input supply voltage can ring dramatically
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 con-
nections between the sense resistor and the LTC4252’s VEE
and SENSE pins are strongly recommended. The drawing in
Figure 8 illustrates the correct way of making connections
between the LTC4252 and the sense resistor. PCB layout
should be balanced and symmetrical 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 9 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
MOSFET CISS (pF)
0
COMPENSATION
CAPACITANCE
C
(nF)
60
50
40
30
20
10
0
2000
4000
425212 F07
6000
8000
NTY100N10
IRF3710
IRF540S
IRF530S
IRF740
Figure 7. Recommended Compensation
Capacitor CC vs MOSFET CISS
Figure 8. Making PCB Connections to the Sense Resistor
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
425212 F08
time point 1, the supply ramps up, together with UV/OV,
VOUT and DRAIN. VIN and PWRGD follow at a slower rate
as set by the VIN bypass capacitor. At time point 2, VIN
exceeds VLKO and the internal logic checks for UV > VUVHI,
OV < VOVLO, GATE < VGATEL, SENSE < VCB, SS < 20 VOS
and TIMER < VTMRL. If all conditions are met, an initial
timing cycle starts and the TIMER capacitor is charged
by a 5.8μA current source pull-up. At time point 3, TIMER
reaches the VTMRH threshold and the initial timing cycle
terminates. The TIMER capacitor is quickly discharged. At
time point 4, the VTMRL threshold is reached and the condi-
tions of GATE < VGATEL, SENSE < VCB and SS<20VOS
must be satisfied before a GATE ramp-up cycle begins.
SS ramps up as dictated by RSS CSS (as in Equation 6);
GATE is held low by the analog current limit (ACL) ampli-
fier until SS crosses 20 VOS. Upon releasing GATE, 58μA
sources into the external MOSFET gate and compensation
network. When the GATE voltage reaches the MOSFET’s
threshold, current begins flowing into the load capacitor
at time point 5. At time point 6, load current reaches the
SS control level and the analog current limit loop activates.
Between time points 6 and 8, the GATE voltage is servoed,
the SENSE voltage is regulated at VACL(t) (Equation 7) and
soft-start limits the slew rate of the load current. If the
SENSE voltage (VSENSE – VEE) reaches the VCB threshold
at time point 7, the circuit breaker TIMER activates. The
TIMER capacitor, CT, is charged by a (230μA + 8 IDRN)
current pull-up. As the load capacitor nears full charge,
load current begins to decline.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4252-2CMSPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
| LTC4252-2CMSTR | 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
| LTC4252-2CMSTRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
| LTC4252-2IMS | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 10MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4252-2IMS#PBF | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
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