DS80PCI800: Solution suggestion for PCIE redriver

Karlchang

Prodigy 170 points

Part Number: DS80PCI800
Other Parts Discussed in Thread: DS80PCI810, DS80PCI402

We have a new project need to use PCIE re-driver in a PCIEx16 case.

I am evaluating DS80PCI800,could I use this part in my new project ?

Or you have suggestions for other parts ?

Channel length :

CPU board 3400mil +Brdige board 664+9675mil=13739 mil

Conservative estimate 1.6~1.7 Inch

over 7 years ago

0 Lee Sledjeski over 7 years ago

TI__Mastermind 43795 points

Hi Karl,

I would recommend to use the DS80PCI810 as the primary design device. This device will work well with this level of channel loss ( ~ 22 dB).

The DS80PCI800 is also a good device to use and they are pin 2 pin compatible.

Regards,

Lee

0 Wu Rain over 7 years ago in reply to Lee Sledjeski

Prodigy 130 points

Hi Lee
1. Is there any known issue in DS80PCI810 ?
2. How about the preset issue in DS80PCI810 ,any improve ?
because we have some experiences in DS80PCI402 and DS80PCI800 ,they can't pass the preset test.
DS80PCI402 only pass TX preset 4 ,and DS80PCI800 can't pass P0,P1,P9,P10.
3. DS80PCI810 and DS80PCI800 pin to pin compatible ? If I encounter problems on DS80PCI810,could I replace DS80PCI800 without PCB or component modified ?

0 Lee Sledjeski over 7 years ago in reply to Wu Rain

TI__Mastermind 43795 points

Hi Wu,

There are no known issues with the DS80PCI810

The DS80PCI810 can pass all presets when connected to a PCIe Transmitter capable of transmitting all the presets correctly.

The DS80PCI810 and DS80PCI800 have the same pinout. Only slight Pin or SMbus configuration changes may be needed.

Regards,

Lee

0 Wu Rain over 7 years ago in reply to Lee Sledjeski

Prodigy 130 points

Hi Lee

OK,thanks
Could I rout trace impedance 85 ohm ?the datasheet is recommend rout to 100 ohm(85-110 ohm)
Just confirm again with you

0 Wu Rain over 7 years ago in reply to Wu Rain

Prodigy 130 points

Does DS80PCI800/810 supported Polarity Inversion (P/N) for easy routing ?

0 Lee Sledjeski over 7 years ago in reply to Wu Rain

TI__Mastermind 43795 points

Hi Wu,

Yes most PCIe applications utilize 85 Ohm impedance targets. This will work well with the PCI800.

Regards,

Lee

0 Lee Sledjeski over 7 years ago in reply to Wu Rain

TI__Mastermind 43795 points

Hi Wu,

The DS80PCI800 or DS80PCI810 do not monitor the PCIe protocol and decoding. So they can be routed as inverted or non-inverted to make fo rthe easiest PCB routing.

Regards,

Lee

0 Wu Rain over 7 years ago in reply to Lee Sledjeski

Prodigy 130 points

Hi Lee

I'm doing PCB layout now ,need your help as soon as possible.thanks

According to Intel PCIE layout guide they require RX pair 0,1 as a bundles ,pair 2,3 as a bundles...etc ...and 0.5 inch length matching within bundles

TX is not required

I set DS80PCI800 in a pin control mode ,so EQ, or DEM value will be the same in CHA or CHB

So the question is do I routing with a bundle rule on CHA and CHB pairs at re-driver input side and output side ?

What is the correct way?

Or just follow intel design guide , length mismatching between pairs will covered by PCIE gen3 auto link tranning ?

Rain

0 Lee Sledjeski over 7 years ago in reply to Wu Rain

TI__Mastermind 43795 points

Hi Rain,

You should still follow the Intel bundle recommendations to match the total channel length for PCIe 0-1, 2-3, etc. I recommend to keep the length mismatch between bundles connected through CHA (0-1, 2-3) and CHB (4-5, 6-7) down to 0.5 inch as well if possible. This will allow you to look at the link training results and see that all the channels are behaving approximately the same.

Regards,

Lee

0 Wu Rain over 7 years ago in reply to Lee Sledjeski

Prodigy 130 points

Hi Lee

What's your means about match the total channel length ?
bundle rule only at redriver input side and output side independent ?
or PCIE host-->redriver-->PCIE device ,the sum of the entire channel?

thanks

0 Lee Sledjeski over 7 years ago in reply to Wu Rain

TI__Mastermind 43795 points

Hi Rain,

The bunde rule should apply to the receiver input side + the output side = total channel length.

For example

Bundle 0-1: CPU -> 10" -> PCI810 -> 10" -> EP

Bundle 2-3: CPU -> 9" -> PCI810 -> 11" -> EP (Option 1)

Bundle 2-3: CPU -> 11" -> PCI810 -> 9" -> EP (Option 2)

All have the same total length of 20"

In the system set the total length within 0.5" to meet the Intel bundle specification.

I recommend to keep the CPU <-> PCI810 distance within 1"

Regards,

Lee

0 Wu Rain over 7 years ago in reply to Lee Sledjeski

Prodigy 130 points

Hi Lee

thank you !
I think the reason may be like this , please correct me if any error

PCIE gen3 auto tranning is operated between CPU and PCIE device
they could not detect re-driver as a PCIE device and re-driver also do not have tranning mechanism
so "The bunde rule should apply to the receiver input side + the output side = total channel length."

0 Wu Rain over 7 years ago in reply to Lee Sledjeski

Prodigy 130 points

Hi Lee
I summarize the 2 rules need to follow according to your narrative ,I hope do not misunderstood what you mean.

Rule1:
in CHA , bundle(0-1) and bundle(2-3) length kept mismatch within 1 inch(as your recommend) whatever PCI810 input or output side respectively
The length of each pair (0,1,2,3) will not exceed the 1 inch in CHA because pin mode just control same EQ,DEM in CHA(pair 0,1,2,3)

IN CHB also the same

Rule2:
Follow INTEL SPEC , total channel ( input + output side)should also kept length mismatch within 0.5 inch
for pair 0 -1(bundle0) ,2-3(bundle2),...6-7(bundle4)

0 Lee Sledjeski over 7 years ago in reply to Wu Rain

TI__Mastermind 43795 points

Hi Wu,

Yes your summary is accurate.

Regards,

Lee

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DS80PCI800: Solution suggestion for PCIE redriver