參數(shù)資料
型號(hào)： LM20144MH
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 穩(wěn)壓器
英文描述： 4A, PowerWise㈢ Adjustable Frequency Synchronous Buck Regulator
中文描述： 6.6 A SWITCHING REGULATOR, 1650 kHz SWITCHING FREQ-MAX, PDSO16
封裝： TSSOP-16
文件頁(yè)數(shù)： 11/20頁(yè)
文件大?。?/td> 744K
代理商： LM20144MH
perature is exceeded. When activated, typically at 160°C, the
LM20144 tri-states the power FETs and resets soft start. After
the junction cools to approximately 150°C, the part starts up
using the normal start up routine. This feature is provided to
prevent catastrophic failures from accidental device over-
heating.
LIGHT LOAD OPERATION
The LM20144 offers increased efficiency when operating at
light loads. Whenever the load current is reduced to a point
where the peak to peak inductor ripple current is greater than
two times the load current, the part will enter the diode emu-
lation mode preventing significant negative inductor current.
The point at which this occurs is the critical conduction bound-
ary and can be calculated by the following equation:
Several diagrams are shown in
Figure 1
illustrating continu-
ous conduction mode (CCM), discontinuous conduction
mode, and the boundary condition.
It can be seen that in diode emulation mode, whenever the
inductor current reaches zero the SW node will become high
impedance. Ringing will occur on this pin as a result of the LC
tank circuit formed by the inductor and the parasitic capaci-
tance at the node. If this ringing is of concern an additional
RC snubber circuit can be added from the switch node to
ground.
At very light loads, usually below 100 mA, several pulses may
be skipped in between switching cycles, effectively reducing
the switching frequency and further improving light-load effi-
ciency.
30030605
FIGURE 1. Modes of Operation for LM20144
11
www.national.com
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM20144MH/NOPB 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
LM20144MHE 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 2.95V to 5.5V 16-Pin TSSOP EP T/R
LM20144MHE/NOPB 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
LM20144MHX 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 2.95V to 5.5V 16-Pin TSSOP EP T/R
LM20144MHX/NOPB 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
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