LMH1228: EQ readback error in Adaptive EQ mode

Takahiro Saito

Part Number: LMH1228

Hi team,

My customer found the EQ readback register(0x52) shows 0x00 once out of few times in the condition of 30 inches trace length. Normally, they can see 0x40 in 0x52 register. However, sometimes 0x52 register shows 0x00 and occur a transmission error.

Customer think adaptive EQ couldn't equalize sufficiently against the decay in the trace.

Could you give me your opinion about this issue? If you know any workaround to solve this issue, could you also please advise me?

Regards,

Saito

over 5 years ago

0 Nasser Mohammadi over 5 years ago

TI__Guru* 93670 points

Hi Saito-San,

Please send us register dump or LMH1228 register contents when reg 0x52 shows 0x00 value while using 30" of FR4 trace length.

Regards,, Nasser

0 Takahiro Saito over 5 years ago in reply to Nasser Mohammadi

TI__Expert 5455 points

Hi Nasser-san,

I'm asking customer the register dump when 0x52 shows 0x00. I will share it with you once I get it.

I have one information about VEO and HEO.

When adaptive EQ works well, VEO is 281.25mV (0x28 = 5A). However, when 0x52 shows 0x00, VEO is 188.5mV (0x28 = 3A). It looks HEO is not different between both cases. (HEO = 0.66UI).

Regards,

Saito

0 Nasser Mohammadi over 5 years ago in reply to Takahiro Saito

TI__Guru* 93670 points

Hi Saito-San,

Please ask your customer to let you know different insertion loss of their FR4 trace length at 6GHz. Please send me internal email to discuss this customer specific data.

Regards,, Nasser

0 Takahiro Saito over 5 years ago in reply to Nasser Mohammadi

TI__Expert 5455 points

Hi Nasser-san,

I will check the insertion loss at 6GHz to customer.

I will send you an email once I get it.

Regards,

Saito

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LMH1228: EQ readback error in Adaptive EQ mode