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参数资料
| 型号： | LTC4219IDHC-5#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| 封装： | 5 X 3 MM, LEAD FREE, PLASTIC, MO-229WJED-1, DFN-16 |
| 文件页数： | 5/18页 |
| 文件大小： | 195K |
| 代理商： | LTC4219IDHC-5#PBF |
LTC4219
13
4219fb
APPLICATIONS INFORMATION
Tying the TIMER pin to INTVCC will force the part to use
the internally generated (circuit breaker) delay of 2ms.
In either case the FLT pin is pulled low to indicate an
overcurrent fault has turned off the pass MOSFET. For a
given circuit breaker time delay, the equation for setting
the timing capacitor’s value is as follows:
CT = tCB 0.083(μF/ms)
After the switch is turned off, the TIMER pin begins dis-
charging the timing capacitor with a 2μA pull-down current.
When the TIMER pin reaches its 0.2V threshold, an internal
100ms timer is started. After the 100ms delay, the switch
is allowed to turn on again if the overcurrent fault has been
cleared. Bringing the EN1 pin above 1.235V and then low
will clear the fault. If the TIMER pin is tied to INTVCC then
the switch is allowed to turn on again (after an internal
100ms delay) if the overcurrent fault is cleared.
The waveform in Figure 4 shows how the output latches
off following a short-circuit. The current in the MOSFET
is 1.4A as the timer ramps up.
temperature which corresponds to a 5.6A current limit at
room temperature.
An external resistor placed between the ISET pinandground
forms a resistive divider with the internal 20k sourcing
resistor. The divider acts to lower the voltage at the ISET
pin and therefore lower the current limit threshold. The
overall current limit threshold precision is reduced to ±12%
when using a 20k resistor to halve the threshold.
Using a switch (connected to ground) in series with this
external resistor allows the active current limit to change
only when the switch is closed. This feature can be used
when the start-up current exceeds the typical maximum
load current.
Monitor MOSFET Temperature
The voltage at the ISET pin increases linearly with increas-
ing temperature. The temperature prole of the ISET pin is
shown in the Typical Performance Characteristics section.
Using a comparator or ADC to measure the ISET voltage
provides an indicator of the MOSFET temperature.
There is an over-temp circuit in the LTC4219 that monitors
an internal voltage similar to the ISET pin voltage. When
the die temperature exceeds 145°C the circuit turns off
the MOSFET until the temperature drops to 125°C.
Monitor MOSFET Current
The current in the MOSFET passes through an internal sense
resistor. The voltage on the sense resistor is converted to
a current that is sourced out of the IMON pin. The gain of
ISENSE amplier is 20μA/A referenced from the MOSFET
current. This output current can be converted to a voltage
using an external resistor to drive a comparator or ADC.
The voltage compliance for the IMON pin is from 0V to
INTVCC – 0.7V.
A microcontroller with a built-in comparator can build a
simple integrating single-slope ADC by resetting a capaci-
tor that is charged with this current. When the capacitor
voltage trips the comparator and the capacitor is reset, a
timer is started. The time between resets will indicate the
MOSFET current.
Current Limit Adjustment
The default value of the active current limit is 5.6A. The
current limit threshold can be adjusted lower by placing
a resistor between the ISET pin and ground. As shown in
the Functional Diagram the voltage at the ISET pin (via
the clamp circuit) sets the CS amplier’s built-in offset
voltage. This offset voltage directly determines the active
current limit value. With the ISET pin open, the voltage at
the ISET pin is determined by a positive temperature co-
efcient reference. This voltage is set to 0.618V at room
Figure 4. Short-Circuit Waveform
AVGATE
10V/DIV
IOUT
2A/DIV
VOUT
10V/DIV
TIMER
2V/DIV
1ms/DIV
4219 F04
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相关代理商/技术参数 |
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| LTC4219IDHC-5-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:5A Integrated Hot Swap Controller |
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| LTC4221CGN | 功能描述:IC CTRLR HOTSWAP DUAL 16SSOP RoHS:否 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 |
| LTC4221CGN#PBF | 功能描述:IC CTLR HOT SWAP DUAL 16SSOP 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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