SN65LVEP11: LVDS Input Requirements

Callum Little

Part Number: SN65LVEP11

Tool/software:

Datasheet for this component specifies that an LVDS signal input is an option but doesn't provide any input requirements for that LVDS mode.
Are these LVDS input requirements available for this component?

3 months ago

0 Vishesh Pithadiya 3 months ago

TI__Mastermind 45871 points

Hi,

This is an older part, so resources may be limited. I will look into this and see what I can find.

0 Brian Zhou 3 months ago

TI__Guru**** 151750 points

HI Callum:

This is LVDS to LVPE conversion.

Regards

brian

0 Callum Little 3 months ago in reply to Brian Zhou

Prodigy 20 points

Hi Brian,

Thank you for this, this is helpful but the SN65LVEP11 component specifies in the datasheet that it can handle an LVDS input, so I was hoping to avoid converting to PECL. However the datasheet does not provide any more information on level requirements for an LVDS input. This is the information I was looking for.

Thanks,

-Callum

0 Brian Zhou 3 months ago in reply to Callum Little

TI__Guru**** 151750 points

Hi Callum:

the common mode voltage between LVDS and LVPECL is different, you can not connect LVDS output directly to LVPPECL input.

Best

Brian

0 Callum Little 3 months ago in reply to Brian Zhou

Prodigy 20 points

Hi, Yes this makes sense, however the datasheet for this part states that it is LVDS input compatible in the features list. With this being the case is there levels defined for this part to ensure we are meeting them with an lvds signal?

0 Brian Zhou 3 months ago in reply to Callum Little

TI__Guru**** 151750 points

If the LVDS signal is 400mv single ended with 1.2v CM, high voltage is 1.450v and low voltage is 0.95V. For LVPECL , 1.45v can not meet min Vih voltage 2.135V.

I believe data sheet was copied from some LVDS datasheet and forgot to remove LVDS completely.

You can place pullup/pulldown resistor on schematic and not installed on PCB to check if it works. If not working, then place resistor back

Regards

brian

0 Callum Little 3 months ago in reply to Brian Zhou

Prodigy 20 points

If the VCC of the SN65lvep11 component is set to 2.5V we would be meeting the VIH and VIL with a 1.2V CM LVDS signal though correct?

0 Vishesh Pithadiya 3 months ago in reply to Callum Little

TI__Mastermind 45871 points

Hi Callum,

We can see that even if the common mode can be set to the same level the swing levels will not be 1:1 compatible. Please use the input circuitry to implement LVDS in this part. Otherwise this application will not work as expected.

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SN65LVEP11: LVDS Input Requirements