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参数资料
| 型号： | LTC4280IUFD |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC24 |
| 封装： | 4 X 5 MM, PLASTIC, MO-220, QFN-24 |
| 文件页数： | 6/28页 |
| 文件大小： | 286K |
| 代理商： | LTC4280IUFD |
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LTC4280
14
4280f
APPLICATIONS INFORMATION
When the MOSFET is turning on, the inrush current follows
the foldback prole as shown in Figure 2. Meanwhile the
FILTER pin is held low with 0.6mA to prevent the FILTER
pin from generating an overcurrent fault during start-up.
The TIMER pin integrates at 100μA during start-up and
once it reaches its threshold of 1.235V, the part checks
to see if it is in current limit, which indicates that it has
started up into a short-circuit condition. If this is the case,
the overcurrent fault bit, D2 in Table 5, is set and the part
turns off. If the part is not in current limit, the FILTER pin
is released to enable circuit breaker and current limit based
overcurrent faults. Alternately an internal 100ms start-up
timer may be selected by tying the TIMER pin to INTVCC.
a 20μA pull-up current from the gate pin slews the gate
upwards and the part is not in current limit. The start-up
TIMER may expire in this condition and an OC fault is not
generated even though start-up has not completed. Either
the sense voltage increases to the 25mV CB threshold or
the current limit as set by the FB pin which generates an
OC fault when the FILTER pin reaches its 1.235V threshold,
or the FB pin voltage crosses its 1.235V power good
threshold and the GPIO pin signals power good.
GATE Pin Voltage
A curve of gate-to-source drive vs VDD is shown in the
Typical Performance Characteristics. At minimum input
supply voltage of 2.9V, the minimum gate-to-source drive
voltage is 4.7V. The gate-to-source voltage is clamped
below 6.5V to protect the gates of logic level N-channel
MOSFETs.
Turn-Off Sequence
The GATE is turned off by a variety of conditions. A normal
turn-off is initiated by the ON pin going low or a serial bus
turn-off command. Additionally, several fault conditions
turn off the GATE. These include an input overvoltage
(OV pin), input undervoltage (UV pin), overcurrent circuit
breaker (SENSE– pin), or EN transitioning high. Writing
a logic one into the UV, OV or OC fault bits (D0-D2 in
Table 5) also latches off the GATE if their auto-retry bits
are set to false.
Normally the MOSFET is turned off with a 1mA current
pulling down the GATE pin to ground. With the MOSFET
turned off, the SOURCE and FB voltages drop as CL
discharges. When the FB voltage crosses below its
threshold, GPIO pulls low to indicate that the output power
is no longer good.
If the VDD pin falls below 2.74V for greater than 2μs or
INTVCC drops below 2.60V for greater than 1μs, a fast shut
down of the MOSFET is initiated. The GATE pin is pulled
down with a 450mA current to the SOURCE pin.
VDD + 6V
VGATE
VOUT
GPIO1
(POWER GOOD)
ILOAD RSENSE
VDD
VSENSE
25mV
10mV
FB
LIMITED
4280 F02
TIMER
EXPIRES
tSTARTUP
Figure 2. Power-Up Waveforms
As the SOURCE voltage rises, the FB pin follows as set
by R7 and R8. Once FB crosses its 1.235V threshold, and
the start-up timer has expired, the GPIO pin, in its default
conguration, ceases to pull low and indicates that power
is now good.
If R6 and C1 are employed for a constant current during
start-up, which produces a constant dV/dt at the output,
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4280IUFD#PBF | 功能描述:IC HOT SWAP CONTROLLER 24-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| LTC4280IUFD#TRPBF | 功能描述:IC CTLR HOT SWAP I2C MON 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| LTC4280IUFD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Hot Swap Controller with I2C Compatible Monitoring |
| LTC4280IUFD-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:Hot Swap Controller with I2C Compatible Monitoring |
| LTC4280IUFD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Hot Swap Controller with I2C Compatible Monitoring |
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