LMK00338: Vcross doesn't meet PCIe gen5 spec

Kazuki Itoh

Genius 10005 points

Part Number: LMK00338
Other Parts Discussed in Thread: LMK00334

Hi team,

My customer wonders LMK00338 Vcross specification doesn't meet PCIe gen5 requirement.

Vcross is different from PCIe specification.

Looking at PCIe Gen4（Refclk DC Specification and AC Timing Requirements Table 8-16）or Gen5(Table 8-17) requirement,

it is specified as : Vcross Absolute crossing point voltage min +250mV max +550mV.

The output specification is 90mV less than PCIe spec, so minimum value doesn't meet PCIe spec.

Why it doesn't meet PCIe spec while LMK00338 is supposed to support PCIe gen5?

Best regards,

Itoh

over 1 year ago

0 Asim Khan over 1 year ago

TI__Genius 9250 points

Hi Itoh,

Let me check internally for this data on this device. Because this uses same die as LMK00334 device which has correct specifications. This could be typo in the datasheet that needs to be fixed. I will verify data on this device and update this accordingly.

Best,

Asim

0 Kazuki Itoh over 1 year ago in reply to Asim Khan

TI__Genius 10005 points

Hi Asim-san,

Do you have any update on this?

Regards,
Itoh

0 Asim Khan over 1 year ago in reply to Kazuki Itoh

TI__Genius 9250 points

Hi Itoh-san,

I checked internally and there is no difference between LMK00334 and LMK00338 initially. I am trying to find out if there was specific data that caused this change or it was an error in datasheet. I will have an update by end of this week.

Best,

Asim

0 Kazuki Itoh over 1 year ago in reply to Asim Khan

TI__Genius 10005 points

Hi Asim-san,

Do you have any update on this?

Regards,

Itoh

0 Asim Khan over 1 year ago in reply to Kazuki Itoh

TI__Genius 9250 points

Hi Kazuki San,

Yes, I have found data on this part. I think confusion in the datasheet could be due to 2.5 V power supply. I have checked data at 3.3 V and its compliant with the standard there is no issue. I will update datasheet with correct values. It will take about three weeks for updated datasheet to appear on ti.com.

Best,

Asim

Clock & timing

Clock & timing forum

LMK00338: Vcross doesn't meet PCIe gen5 spec