参数资料
型号: L5986
厂商: STMICROELECTRONICS
元件分类: 稳压器
英文描述: 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
封装: 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, VFQFP-8
文件页数: 16/38页
文件大小: 1067K
代理商: L5986
L5986
Application information
Doc ID 14971 Rev 3
23/38
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 1 k and 5 k, 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 22
Where fESR is the ESR zero:
Equation 23
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 24
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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L5987 功能描述:直流/直流开关调节器 3 A buck switching regulator RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5987A 功能描述:直流/直流开关调节器 3 A STEP-DOWN SWITCH REG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5