參數(shù)資料
型號(hào): LM5007MM
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類: 穩(wěn)壓器
英文描述: High Voltage (80V) Step Down Switching Regulator
中文描述: 0.9 A SWITCHING REGULATOR, PDSO8
封裝: MSOP-8
文件頁數(shù): 7/12頁
文件大?。?/td> 230K
代理商: LM5007MM
High Voltage Bias Regulator
(Continued)
Over-Voltage Comparator
The over-voltage comparator is provided to protect the out-
put from overvoltage conditions due to sudden input line
voltage changes or output loading changes. The over-
voltage comparator monitors the FB pin versus an internal
2.875V reference (OV_REF). If the voltage at FB rises above
OV_REF the comparator immediately terminates the buck
switch on time pulse.
ON Time generator and Shutdown
The on time of the LM5007 is set inversely proportional to
the input voltage by an external resistor connected between
Ron and Vin. The Ron terminal is a low impedance input
biased at approximately 1.5V. Thus the current through the
resistor and into the Ron terminal is approximately propor-
tional to Vin and used internally to control the on timer. This
scheme of input voltage feed-forward hysteretic operation
achieves nearly constant operational frequency over varying
line and load conditions. The on time equation for the
LM5007 is :
Ton = 1.42 x 10
-10
x R
ON
/ V
IN
The R
ON
pin of the LM5007 also provides a shutdown func-
tion which disables the regulator and significantly decreases
quiescent power dissipation. By pulling the R
ON
pin to below
0.7V logic threshold activates the low power shutdown
mode. The V
IN
quiescent current in the shutdown mode is
approximately 100μA internal to the LM5007 plus the current
in the R
ON
resistor.
20078306
FIGURE 2. Self Biased Configuration
L
www.national.com
7
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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LM5007MMEP 制造商:Texas Instruments 功能描述:STEP DOWN SWITCHING REG 80V 5007
LM5007MMX 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