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AWR2243: LC Filter design on VIN_13RF1/2 with LP87524P-Q1

Yudai
Prodigy 100 points
Part Number: AWR2243
Other Parts Discussed in Thread: LP87524P-Q1,

Hi

I'd like to know LC Filter design on AWR2243's VIN_13RF1/2 with LP87524P-Q1.
There seems to be a difference between the specification sheet and the development board design policy.
Could you tell me following question one by one for me?

①Any recommendations for L and C constants on the output voltage line?

According to the specifications below, L is 470uH, Cout is 22uF, and Cpol is 100uF or less.
https://www.ti.com/lit/ds/symlink/lp87524p-q1.pdf?ts=1662353734239&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252Fja-jp%252FLP87524P-Q1

However, in the development board schematic, it looks like L is 470uH, Cout is 22uF +22uF, and Cpol is missing.
https://www.ti.com/tool/ja-jp/MMWCAS-RF-EVM#tech-docs

②Any recommendations for L and C constants of filter on the input voltage line for VIN_13RF1/2 ?
The specifications below recommend ferrite beads.
https://www.ti.com/jp/lit/an/swra577a/swra577a.pdf?ts=1662340113089&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252Fja-jp%252FLP87524Q1EVM

However, the schematic for the development board looks like it has an LC filter on it.
https://www.ti.com/tool/ja-jp/MMWCAS-RF-EVM#tech-docs


③How to determine the design frequency of an LC filter on the input voltage line for VIN_13RF1/2 ?
In the document below, it looks like you are designing a 100-200KHz ferrite bead while paying attention to the noise after signal processing.
What is 113.9KHz?(Pole Frequencies w.r.t. 1V Rail Decaps/1.8V Rail Decaps (KHz) )

https://www.ti.com/jp/lit/an/swra577a/swra577a.pdf?ts=1662340113089&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252Fja-jp%252FLP87524Q1EVM



Thanks

  • 0
    TI__Genius 13675 points

    Hi,

                   Few comments

    1. Please refer the PMIC EVM schematic for more close comparison.

    2. The recommendations is for single chip EVM, where as the EVM you are comparing it with is a multi chip cascaded design where the rails is shared between 2 devices. Hence they need to be also isolated from each other from noise perspective.

    Regards