- 您现在的位置：买卖IC网 > PDF目录179918 > LTC4252-2CMS8#TRPBF (LINEAR TECHNOLOGY CORP) Negative Voltage Hot Swap Controllers; Package: MSOP; No of Pins: 8; Temperature Range: 0°C to +70°C PDF资料下载
参数资料
| 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： | 11/36页 |
| 文件大小： | 336K |
| 代理商： | LTC4252-2CMS8#TRPBF |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页当前第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页
LTC4252-1/LTC4252-2
LTC4252A-1/LTC4252A-2
19
425212fc
APPLICATIONS INFORMATION
A low impedance short on one card may influence the
behavior of others sharing the same backplane. The initial
glitch and backplane sag as seen in Figure 6 Trace 1, can
rob charge from output capacitors on adjacent cards.
When the faulty card shuts down, current flows in to
refresh the capacitors. If LTC4252s are used by the other
cards, they respond by limiting the inrush current to a
value of 100mV/RS. If CT is sized correctly, the capacitors
will recharge long before CT times out.
POWER GOOD, PWRGD
PWRGD latches low if GATE charges up to within 2.8V of
VIN and DRAIN pulls below VDRNL during start-up. PWRGD
is reset in UVLO, in a UV condition or if CT charges up
to 4V. An overvoltage condition has no effect on PWRGD
status. A 58μA current pulls this pin high during reset.
Due to voltage transients between the power module and
PWRGD,optoisolationisrecommended.Thispinprovides
sufficent drive for an optocoupler. Figure 19 shows an
alternative NPN configuration with a limiting base resistor
for the PWRGD interface. The module enable input should
have protection from the negative input current.
MOSFET SELECTION
The external MOSFET switch must have adequate safe
operating area (SOA) to handle short-circuit conditions
until TIMER times out. These considerations take prece-
dence over DC current ratings. A MOSFET with adequate
SOA for a given application can always handle the required
current, but the opposite may not be true. Consult the
manufacturer’s MOSFET data sheet for safe operating
area and effective transient thermal impedance curves.
MOSFET selection is a 3-step process by assuming the
absense of a soft-start capacitor. First, RS is calculated
and then the time required to charge the load capacitance
is determined. This timing, along with the maximum
short-circuit current and maximum input voltage defines
an operating point that is checked against the MOSFET’s
SOA curve.
To begin a design, first specify the required load current
and Ioad capacitance, IL and CL. The circuit breaker cur-
rent trip point (VCB/RS) should be set to accommodate
the maximum load current. Note that maximum input
current to a DC/DC converter is expected at VSUPPLY(MIN).
RS is given by:
RS =
VCB(MIN)
IL(MAX)
(8)
where VCB(MIN) = 40mV (45mV for LTC4252A) represents
the guaranteed minimum circuit breaker threshold.
During the initial charging process, the LTC4252 may oper-
ate the MOSFET in current limit, forcing (VACL) between
80mV to 120mV (VACL is 54mV to 66mV for LTC4252A)
across RS. The minimum inrush current is given by:
IINRUSH(MIN)=
80mV
RS
(9)
Maximum short-circuit current limit is calculated using
the maximum VACL. This gives
ISHORTCIRCUIT(MAX)=
120mV
RS
(10)
The TIMER capacitor CT must be selected based on the
slowest expected charging rate; otherwise TIMER might
time out before the load capacitor is fully charged. A value
for CT is calculated based on the maximum time it takes
the load capacitor to charge. That time is given by:
tCL(CHARGE) =
C V
I
=
CL VSUPPLY(MAX)
IINRUSH(MIN)
(11)
The maximum current flowing in the DRAIN pin is given by:
IDRN(MAX) =
V SUPPLY(MAX)–VDRNCL
RD
(12)
相关PDF资料 |
PDF描述 |
|---|---|
| LTC4252-2IMS8#PBF | Negative Voltage Hot Swap Controllers; Package: MSOP; No of Pins: 8; Temperature Range: -40°C to +85°C |
| LTC4252-2IMS8#TRPBF | Negative Voltage Hot Swap Controllers; Package: MSOP; No of Pins: 8; Temperature Range: -40°C to +85°C |
| LTC4253ACGN-ADJ#PBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 20; Temperature Range: 0°C to +70°C |
| LTC4253ACGN-ADJ#TRPBF | -48V Hot Swap Controller with Sequencer; Package: SSOP; No of Pins: 20; Temperature Range: 0°C to +70°C |
| LTC4253ACUF-ADJ#PBF | -48V Hot Swap Controller with Sequencer; Package: QFN; No of Pins: 20; Temperature Range: 0°C to +70°C |
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 |
发布紧急采购，3分钟左右您将得到回复。