DS280DF810: DS280DF810 - internal eye mask requirement

Jason Dai

Part Number: DS280DF810

Dear E2E,

What is the requirement of internal eye diagram in DS280DF810?

VEO>200mV and HEO>0.44UI

my question is that is it must to meet both requirement. what if only meet one of criteria, which one is more important?

in fact, we tried a lot of setting of FIR combination in ASIC, but the internal eye of Retimer still can't meet both requirement. only pass HEO criteria.

the insertion loss is less than 35dB.

any tip or direction can improve the internal eye diagram?

BR,

Jason

over 7 years ago

0 Michael Lu (Santa Clara) over 7 years ago

TI__Mastermind 29655 points

Hi Jason,

After the CTLE + DFE, I believe the HEO and VEO appear you have specified should be sufficient for error-free operation. Both HEO and VEO are important, though I believe the HEO is a greater indicator of whether error-free operation can be achieved.

1. What are the settings you are currently using in the DS280DF810 (CTLE boost settings, DFE tap settings, etc.)

2. Can you describe the loss for the entire signal path before the DS280DF810?

3. Are you currently experiencing bit errors in your system with the current settings?

Thanks,

Michael

0 Rodrigo Natal over 7 years ago in reply to Michael Lu (Santa Clara)

TI__Mastermind 19235 points

Adding to Michael's inputs, the Tx voltage output differential (VOD) and FIR pre-cursor and post-cursor settings will also affect the retimer Rx input eye opening values. Ideally, the Tx VOD, FIR pre-cursor and post settings used are ones that yield optimal Rx BER and eye opening performance.

Cordially,

Rodrigo Natal

HSSC Applications Engineer

0 Jason Dai over 7 years ago in reply to Rodrigo Natal

TI__Expert 3720 points

Michael and Rodrigo,
Please see my reply for those question first.
1. What are the settings you are currently using in the DS280DF810 (CTLE boost settings, DFE tap settings, etc.)
[Jason] we set adaptive mode 1 to let retimer auto find the optimize setting. so, we didn't record it.

2. Can you describe the loss for the entire signal path before the DS280DF810?
[Jason] it is around 30dB loss.

3. Are you currently experiencing bit errors in your system with the current settings?
[Jason] Yes. that's why we separate it into MAC to Retimer, Retimer to Retimer, and Retimer to MAC to debug by checking internal eye.
And, i knew that TX FIR will affect retimer RX input eye. Customer already tried many combination on MAX TX FIR, but retimer RX internal eye is still fail especially on VEO.

Customer question is if they must meet both criteria or meet HEO is enough or something else which could make sure no package loss when package go through our retimer.

VEO>200mV and HEO>0.44UI

0 Rodrigo Natal over 7 years ago in reply to Jason Dai

TI__Mastermind 19235 points

Given your application description I would recommend the following:

Set the retimer to adapt mode 2 and enable the DFE

STEP	SHARED/ CHANNEL REGISTER SET	OPERATION	REGISTER ADDRESS [HEX]	REGISTER VALUE [HEX]	WRITE MASK [HEX]	COMMENT
	Channel	Write	31	40	60	Adapt mode 2
1	Channel	Write	23	40	40	Enable DFE Override
2	Channel	Write	1E	02	0A	Enable DFE (DFE_PD=0) and enable DFE taps 3-5 (EN_PARTIAL_DFE=1)

Set the Tx link partner to voltage output differential in the range of 800mVpp to 1Vpp
Set the Tx link partner to apply some Tx FIR pre-cursor. As a starting point I wouild recommend Tx FIR Rpre in the order of 3dB to 5dB
Set Tx FIR post-cursor to zero

Cordially,

Rodrigo Natal

HSSC Applications Engineer

Interface

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DS280DF810: DS280DF810 - internal eye mask requirement