LMK6H: Regarding LMK6H (LMK6HA10000ADLER) Output to HCSL Receiver With External Termination

Tim Peng

Part Number: LMK6H

Tool/software:

Hi Support

I have question regarding figure 8-9 LMK6H Output to HCSL Receiver With External Termination, Priori to simukation, I would like to clarify since It looks like different from standard HCSL termination from other vendor's application note. I am just wondering if there should be series resistors like my sketch? Or there is already build-in series resistor inside LMK6H?

* I am also attaching the application from other vendor.

1 month ago

0 Connor Lewis 1 month ago

TI__Genius 13240 points

Hi Tim,

For LMK6H you can add a placeholder for series resistors in your schematic. Adding series resistors in the 17-33 Ohm range can help reduce overshoot and ringing in the output, but they aren't strictly required. The optimal value depends on the impedance profile of your traces, board stackup, etc.

Regards,

Connor

0 Tim Peng 1 month ago in reply to Connor Lewis

Prodigy 160 points

Hi Connor,

one more question, I want to validate if the captured time domain waveform from LMK6HA10000ADLER meets PCIe refclk requirement or not. Does TI provide any tool (with clear steps ) to do so?

+1 Connor Lewis 1 month ago in reply to Tim Peng

TI__Genius 13240 points

Hi Tim,

We have a PCIe compliance report for LMK6H here which includes both frequency and time domain measurements: https://www.ti.com/lit/an/snla445/snla445.pdf

There's also a tool built into TICS Pro where you can input phase noise curves or a captured waveform from a scope to check compliance with the PCIe Refclk spec. Most of the necessary time domain specifications are included in the LMK6H datasheet as well (VOH, VOL, crossing point, slew rate, etc.).

Here's where you can find the PCIe tool in TICS Pro: