AM3358: SSC for main MPU

Twinkle Goyal

Part Number: AM3358

Hello,

We have a designed custom board with an AM3358 processor. We are using a 24MHz crystal for providing a clock to the processor. However, we see some EMI peaks observed at Harmonics of 24MHz from the Processor. We want to know if we can enable and use SSC to overcome this. As per AM335x TRM, SSC is available. But we are not sure how to enable it for the core MPU.

Is it possible? If yes, how do we enable it from the Linux kernel source?

Thanks,

Twinkle

over 2 years ago

0 Kallikuppa Sreenivasa over 2 years ago

TI__Guru**** 192179 points

Hello Twinkle

Thank you for the query.

Please note the recomendations in the below section.

8.1.6.6 Spread Spectrum Clocking (SSC)

https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf

Regards,

Sreenivasa

0 Twinkle Goyal over 2 years ago in reply to Kallikuppa Sreenivasa

Prodigy 80 points

Hi Sree,

I did refer to the document and section you mentioned per my post. However, I am still new to SSC and find trouble understanding if enabling SSC in MPU PLL will reduce the overall 24MHz harmonics EMI. Also, I need help in understanding how to enable this via the linux kernel driver.

Thanks

0 Kallikuppa Sreenivasa over 2 years ago in reply to Twinkle Goyal

TI__Guru**** 192179 points

Hello Twinkle

Please refer below. major of the peripherals do not support Spread spectrum.

Spread spectrum clock is only supported for the DISP/LCD and MPU PLLs on this device. Spread spectrum clocking is not supported for DDR, PER, and CORE PLLs. When enabling SSC on MPU PLL, ensure the maximum MPU frequency remains below the maximum rated frequency for the chosen OPP (see the device-specific Data Manual for more details).

Do you use a clock or crystal?

Regards,

Sreenivasa

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AM3358: SSC for main MPU