參數(shù)資料
型號(hào)： L7981ATR
廠商： STMICROELECTRONICS
元件分類(lèi)： 穩(wěn)壓器
英文描述： SWITCHING REGULATOR, DSO8
封裝： 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, HSOP-8
文件頁(yè)數(shù)： 29/44頁(yè)
文件大?。?/td> 1315K
代理商： L7981ATR
L7981
Application ideas
Doc ID 15182 Rev 3
35/44
7
Application ideas
7.1
Positive buck-boost
The L7981 can implement the step up/down converter with a positive output voltage.
Figure 33. shows the schematic: one power MOSFET and one Schottky diode are added to
the standard buck topology to provide 12 V output voltage with input voltage from 4.5 V to 28
V.
Figure 33.
Positive buck-boost regulator
The relationship between input and output voltage is:
Equation 33
So the duty cycle is:
Equation 34
The output voltage isn’t limited by the maximum operating voltage of the device (28 V),
because the output voltage is sense only through the resistor divider. The external power
MOSFET maximum drain to source voltage, must be higher than output voltage; the
maximum gate to source voltage must be higher than the input voltage (in Figure 33., if VIN
is higher than 16V, the gate must be protected through zener diode and resistor)
The current flowing through the internal power MOSFET is transferred to the load only
during the OFF time, so according to the maximum DC switch current (3.0 A), the maximum
output current for the buck boost topology can be calculated from the following equation.
V
OUT
V
IN
D
1D
–
-------------
=
D
V
OUT
V
OUT
V
IN
+
------------------------------
=
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L7981ATR/BLK 制造商:STMicroelectronics 功能描述:3 A STEP-DOWN SWITCHING REGULATO - Tape and Reel 制造商:STMicroelectronics 功能描述:STMicroelectronics L7981ATR/BLK Interface Misc
L7981TR 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 3A DC 4.5 V to 28 V Adj 0.6V 250 kHz RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
L7983 制造商:Leviton Manufacturing Co 功能描述:
L7985 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) 2A Step Down REG 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 輸出類(lèi)型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
L7985A 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2A DC 4.5V to 38V 250 KHz Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
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