參數(shù)資料
型號(hào): L7981TR
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: SWITCHING REGULATOR, DSO8
封裝: 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, VFQFP-8
文件頁數(shù): 18/44頁
文件大?。?/td> 1315K
代理商: L7981TR
L7981
Application informations
Doc ID 15182 Rev 3
25/44
Figure 14.
Open loop gain: module bode diagram
The guidelines for positioning the poles and the zeroes and for calculating the component
values can be summarized as follow:
1.
Choose a value for R1, usually between 1kΩ and 5kΩ, in order to have values of C4
and C5 not comparable with parasitic capacitance of the board.
2.
Choose a gain (R4/R1) in order to have the required bandwidth (BW), that means:
Equation 25
Where fESR is the ESR zero:
Equation 26
and Vs is the saw-tooth amplitude. The voltage feed forward keeps the ratio Vs/Vin constant.
3.
Calculate C4 by placing the zero one decade below the output filter double pole:
Equation 27
4.
Then calculate C3 in order to place the second pole at four times the system bandwidth
(BW):
R
4
f
ESR
f
LC
------------
2
BW
f
ESR
------------
V
S
V
IN
--------- R
1
=
f
ESR
1
2
π ESR C
OUT
--------------------------------------------
=
C
4
10
2
π R
4
f
LC
-------------------------------
=
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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
L7985ATR 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) 2A Step-Down REG 2A DC 4.5 to 38V RoHS:否 制造商:STMicroelectronics 輸出類型: 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
L7985TR 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