LMK3H0102: Does LMK3H0102 in LP-HCSL mode compatible with AM64 PCIe REFCLK input?

Kallikuppa Sreenivasa

Guru**** 215080 points

Part Number: LMK3H0102

Hi Team,

I have a customer query checking on the compatibility LMK3H0102 with the AM64x HCSL input.

SERDES0 REFCLKP/N requires HCSL-level inputs when operating in input mode.

(8) AM6442: AM6442 HCSL vs LP-HCSL PCIe REFCLK - Processors forum - Processors - TI E2E support forums

Please support the query.

FYI, i see the below thread

(+) TDA4AH-Q1: Is Low Power HCSL (LP-HCSL) okay for the SerDes REFCLK inputs? - Processors forum - Processors - TI E2E support forums

Regards,

Sreenivasa

4 months ago

0 Sandra Saba 4 months ago

TI__Intellectual 2830 points

Hi Sreenivasa,

LMK3H0102 (there is no LMK3H0103) can support LP-HCSL with internally selectable 85 Ohm or 100 Ohm termination for PCIe Gen 1 to PCIe Gen 7 compliance.

Please work with the processors team to confirm requirements as I did not see any references for the SERDES0 REFCLKP/N clock requirements on the AM64x datasheet.

For differences between the HCSL and LP-HCSL you can refer to this thread

Best,

Sandra

0 Kallikuppa Sreenivasa 4 months ago in reply to Sandra Saba

TI__Guru**** 215080 points

Hello Sandra,

Thank you.

Please refer below.

(8) AM6442: Serdes input clock (SERDES0_REFCLK) - Processors forum - Processors - TI E2E support forums

HCSL clocking is required when AM644x is operating in clock-input mode.

I understand LMK3H0102 can support LP-HCSL with internally selectable 85 Ohm or 100 Ohm termination for PCIe Gen 1 to PCIe Gen 7 compliance

Sandra Saba said:
For differences between the HCSL and LP-HCSL you can refer to this thread

I understand from the above link the amplitudes are similar.

Based on the above any thoughts if the LMK3H0102 output connected to the AM644x is likely to work (agree this needs to be tested) or do you see some concerns that needs additional analysis.

Regards,

Sreenivasa'

0 Sandra Saba 4 months ago in reply to Kallikuppa Sreenivasa

TI__Intellectual 2830 points

Hi Sreenivasa,

i dont see any concerns for the use of LMK3H0102, and there is no need populate the external termination resistors as you would for the HCSL format

Best,
Sandra

0 Kallikuppa Sreenivasa 4 months ago in reply to Sandra Saba

TI__Guru**** 215080 points

Hello Sandra,

Thank you for the inputs, appreciated.

Regards,

Sreenivasa

0 Sandra Saba 4 months ago in reply to Kallikuppa Sreenivasa

TI__Intellectual 2830 points

forgot to note, if the termination resistors are populated then the swing will get cut in half

0 Kallikuppa Sreenivasa 4 months ago in reply to Sandra Saba

TI__Guru**** 215080 points

Hello Sandra,

Thank you and noted.

I assume you meant populating external terminations affects the amplitude and is not recommended.

Regards,

Sreenivasa

0 Sandra Saba 4 months ago in reply to Kallikuppa Sreenivasa

TI__Intellectual 2830 points

Hi,

Correct.

Best,

Sandra

0 Kallikuppa Sreenivasa 4 months ago in reply to Sandra Saba

TI__Guru**** 215080 points

Hello Sandra,

Thank you.

Regards,

Sreenivasa

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LMK3H0102: Does LMK3H0102 in LP-HCSL mode compatible with AM64 PCIe REFCLK input?