OPT8241: ILLUM_N signal of OPT8241 is not right

Chris_Wang

Part Number: OPT8241
Other Parts Discussed in Thread: OPT9221

Hi guys：

I made a broad which was refer to the OPT8241-CDK-EVM board.But when I measured the ILLUM_N and ILLUM_P signals, I found the square waves in my board were so confusion and strange,but in the OPT8241-CDK-EVM the square waves were standard.Hope U can help me,thanks!

Regards,
Chris

over 7 years ago

0 Subhash Chandra Sadhu over 7 years ago

TI__Expert 3800 points

Hi Chris,

It looks like your board's signal is ringing. Did you check if the board is impedance controlled?

Regards,
Subhash

0 Chris_Wang over 7 years ago in reply to Subhash Chandra Sadhu

Prodigy 180 points

Hi Subhash:

I'm happy to talk with you again,thanks for your help! The single-ended signals have been impedance controlled to 50Ω.

Regards,
Chris

0 Larry Li over 6 years ago in reply to Chris_Wang

TI__Expert 3495 points

Guys, is this issue closed?

0 Chris_Wang over 6 years ago in reply to Larry Li

Prodigy 180 points

Hi Larry:
I referred the OPT8241-CDK-EVM to connected the IO_MOD_REF pin and ILLUM_MOD_FB pin together under the OPT9221 chip.So it's hard to make the two signals separated.And i pull the COMP_MOD_FB to GND, disable delay_fb_corr_mode and delay_fb_dc_corr_mode, but the problem is still in there as long as enable the dealiasing.

0 Larry Li over 6 years ago in reply to Chris_Wang

TI__Expert 3495 points

Dealiasing may the the root cause (bad settings). Please try the attached spread sheet to find all the necessary PLL register setting for dealising setup.

Verify it against your current setting with issue, and see what the difference is.

-Larry

4011.DealiasCalc.xlsx

0 Larry Li over 6 years ago in reply to Larry Li

TI__Expert 3495 points

Hi Chris, checking to see if your issue is resolved.

Sensors

Sensors forum

OPT8241: ILLUM_N signal of OPT8241 is not right