TDA4VM-Q1: eMMC CLK waveform

Xingyu Zhu

Part Number: TDA4VM-Q1

Dear expert,

Our customer find there is some bit-flipping error with using emmc (MTFC32GASAQHD-AAT). They captured below emmc CLK waveform and find it seems being changed from 1.8V to 1.2V (HS200) while the Vccq is constantly 1.8V. Per the emmc datasheet, this chip doesn't support 1.2V. Could you please help to check if this waveform is normal and can we modify it? Thanks.

Best Regards,

Xingyu Zhu

over 2 years ago

0 kcastille over 2 years ago

TI__Guru 55817 points

Hello Xingyu,

This may be partly a measurement artifact. Can you zoom in on the clock during the high amplitude vs lower amplitude points in time? My guess is that there is a frequency change at exactly that time, and the signal does not have enough time to go fully to 1.8V or fully to 0V, thus looking like it's a different voltage setting.

If you measure with a high bandwidth scope+probe, and very short probe and ground leads, you'll probably see the signal look better (higher magnitude).

Regards,

Kyle

0 Xingyu Zhu over 2 years ago in reply to kcastille

TI__Expert 4335 points

Hi Kyle

Thanks for your reply. Below is the zoom-in waveform of 400kHz and 200MHz. It looks like the drive strength is not enough or the load capacitance is too big? Can I modify the Pad config register to increase the drive strength to improve the signal? Or is there any other method? Thanks.