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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： | 18/18页 |
| 文件大小： | 238K |
| 代理商： | LTC4217IFE#PBF |
LTC4217
9
4217fe
operaTion
The Functional Diagram displays the main circuits of the
device. The LTC4217 is designed to turn a board’s supply
voltageonandoffinacontrolledmannerallowingtheboard
to be safely inserted and removed from a live backplane.
The LTC4217 includes a 25mΩ MOSFET and a 7.5mΩ cur-
rent sense resistor. During normal operation, the charge
pump and gate driver turn on the pass MOSFET’s gate to
provide power to the load. The inrush current control is
accomplished by the INRUSH circuit. This circuit limits
the GATE ramp rate to 0.3V/ms and hence controls the
voltage ramp rate of the output capacitor.
The current sense (CS) amplifier monitors the load current
using the voltage sensed across the current sense resistor.
The CS amplifier limits the current in the load by reduc-
ing the GATE-to-OUT voltage in an active control loop. It
is simple to adjust the current limit threshold using the
current setting (ISET) pin. This allows a different threshold
during other times such as start-up.
A short circuit on the output to ground causes significant
power dissipation during active current limiting. To limit
this power, the foldback amplifier reduces the current limit
value from 2A to 0.5A in a linear manner as the FB pin
drops below 0.6V (see the Typical Performance Charac-
teristics section).
If an overcurrent condition persists, the TIMER pin ramps
up with a 100A current source until the pin voltage ex-
ceeds 1.2V (comparator TM2). This indicates to the logic
that it is time to turn off the pass MOSFET to prevent
overheating. At this point the TIMER pin ramps down us-
ing the 2A current source until the voltage drops below
0.2V (Comparator TM1) which tells the logic to start an
internal 100ms timer. At this point, the pass transistor
has cooled and it is safe to turn it on again. It is suitable
for many applications to use an internal 2ms overcurrent
timer with a 100ms cooldown period. Tying the TIMER
pin to INTVCC sets this default timing.
The fixed 12V version, LTC4217-12, uses two separate
internal dividers from VDD to drive the UV and OV pins.
This version also features a divider from OUT to drive the
FB pin. The LTC4217-12 is available in the DFN package
while the LTC4217 (adjustable version) is in the DFN and
TSSOP packages.
The output voltage is monitored using the FB pin and the
PG comparator to determine if the power is available for
the load. The power good condition is signaled by the PG
pin using an open-drain pull-down transistor.
The Functional Diagram also shows the monitoring blocks
of the LTC4217. The two comparators on the left side
include the UV and OV comparators. These comparators
determineiftheexternalconditionsarevalidpriortoturning
on the MOSFET. But first the undervoltage lockout circuits
UVLO1 and UVLO2 must validate the input supply and
the internally generated 3.1V supply (INTVCC) and gener-
ate the power up initialization to the logic circuits. If the
external conditions remain valid for 100ms the MOSFET
is allowed to turn on.
Other features include MOSFET current and temperature
monitoring. The current monitor (CM) outputs a current
proportionaltothesenseresistorcurrent.Thiscurrentcan
drive an external resistor or other circuits for monitoring
purposes. A voltage proportional to the MOSFET tempera-
ture is output to the ISET pin. The MOSFET temperature
allows external circuits to predict failure and shutdown
the system.
applicaTions inForMaTion
The typical LTC4217 application is in a high availability
system that uses a positive voltage supply to distribute
power to individual cards. A complete application circuit
is shown in Figure 1. External component selection is
discussed in detail in the following sections.
Turn-On Sequence
Several conditions must be present before the internal
pass MOSFET can be turned on. First the supply VDD must
exceed its undervoltage lockout level. Next the internally
generated supply INTVCC must cross its 2.65V undervolt-
agethreshold.Thisgeneratesa25spower-on-resetpulse
whichclearsthefaultregisterandinitializesinternallatches.
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PDF描述 |
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| LTC4217IDHC#TR | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| LTC4217CDHC#TR | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| LTC4217HFE#PBF | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO20 |
| LTC4217CDHC | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| LTC4217CDHC-12#TRPBF | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
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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