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参数资料
| 型号： | LTC4217IFE#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO20 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, SSOP-20 |
| 文件页数： | 2/18页 |
| 文件大小： | 238K |
| 代理商： | LTC4217IFE#PBF |
LTC4217
10
4217fe
applicaTions inForMaTion
evident from this graph that the power dissipation at 12V,
300mA for 40ms is in the safe region.
Adding a capacitor and a 1k series resistor from GATE to
groundwilllowertheinrushcurrentbelowthedefaultvalue
set by the INRUSH circuit. The GATE is charged with an
24A current source (when INRUSH circuit is not driving
the GATE). The voltage at the GATE pin rises with a slope
equalto24A/CGATEandthesupplyinrushcurrentissetat:
IINRUSH =
CL
CGATE
24A
When the GATE voltage reaches the MOSFET threshold
voltage, the switch begins to turn on and the OUT volt-
age follows the GATE voltage as it increases. Once OUT
reaches VDD, the GATE will ramp up until clamped by the
6.15V Zener between GATE and OUT.
As the OUT voltage rises, so will the FB pin which is moni-
toring it. Once the FB pin crosses its 1.235V threshold
and the GATE to OUT voltage exceeds 4.2V, the PG pin
will cease to pull low and indicate that the power is good.
Parasitic MOSFET Oscillation
When the N-channel MOSFET ramps up the output dur-
ing power-up it operates as a source follower. The source
follower configuration may self-oscillate in the range of
25kHz to 300kHz when the load capacitance is less than
10F, especially if the wiring inductance from the supply
to the VDD pin is greater than 3H. The possibility of oscil-
lation will increase as the load current (during power-up)
increases. There are two ways to prevent this type of
oscillation. The simplest way is to avoid load capacitances
below 10F. For wiring inductance larger than 20H, the
minimumloadcapacitancemayextendto100F.Asecond
choice is to connect an external gate capacitor CP >1.5nF
as shown in Figure 3.
Turn-Off Sequence
The switch can be turned off by a variety of conditions. A
normal turn-off is initiated by the UV pin going below its
1.235V threshold. Additionally, several fault conditions
will turn off the switch. These include an input overvolt-
age (OV pin), overcurrent circuit breaker (SENSE pin) or
Figure 2. Supply Turn-On
Figure 1. 0.8A, 12V Card Resident Application
Afterthepower-on-resetpulse,theLTC4217willgothrough
the following sequence. First, the UV and OV pins must
indicatethattheinputvoltageiswithintheacceptablerange.
All of these conditions must be satisfied for the duration
of 100ms to ensure that any contact bounce during the
insertion has ended.
The MOSFET is turned on by charging up the GATE with
a charge pump generated current source whose value is
adjusted by shunting a portion of the pull-up current to
ground. The charging current is controlled by the INRUSH
circuit that maintains a constant slope of GATE voltage ver-
sus time (Figure 2). The voltage at the GATE pin rises with
a slope of 0.3V/ms and the supply inrush current is set at:
IINRUSH = CL (0.3V/ms)
This gate slope is designed to charge up a 1000F ca-
pacitor to 12V in 40ms, with an inrush current of 300mA.
This allows the inrush current to stay under the current
limit threshold (500mA) for capacitors less than 1000F.
IncludedintheTypicalPerformanceCharacteristicssection
is a graph of the Safe Operating Area for the MOSFET. It is
R5
150k
R6
20k
ADC
R1
224k
C1
0.1F
R2
20k
12V
4217 F01
R7
10k
CT
0.1F
CL
330F
VOUT
12V
0.8A
VDD
UV
OUT
FB
PG
GND
IMON
RSET
20k
RMON
20k
ISET
CGATE
0.1F
RGATE
1k
GATE
LTC4217FE
OV
INTVCC
TIMER
FLT
+
R3
140k
R4
20k
t1
t2
SLOPE = 0.3V/ms
GATE
OUT
VDD + 6.15
VDD
4217 F02
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4217IFE-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:2A Integrated Hot Swap Controller |
| LTC4217IFE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:2A Integrated Hot Swap Controller |
| LTC4218 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Hot Swap Controller |
| LTC4218CDHC-12#PBF | 功能描述:IC CTLR HOT SWAP 16-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4218CDHC-12#TRPBF | 功能描述:IC CNTRLR HOT SWAP 16-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
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