DS90UB954-Q1: Abs max rating on RIN+ pin on COAX

Kohsuke Hamasaki

Part Number: DS90UB954-Q1

Hi, Team,

From some evaluation,

If Ser starts up faster than Des, the Forward channel is applied to RIN+ of Des which might be violate Abs min value, -0.3V.

It is also same situation at Shutdown when Ser sets power down after Des.

Do you think we should care about this?

Thanks,

Koh

0 Jiashow Ho over 4 years ago

Hi Koh-san,

If in synchronous mode, the ser will not be able to supply the forward channel to des. Where did the -0.3V come from?

You have an AC coupling cap near the device right? The purpose of the AC coupling cap is to block the DC offset that could occur in your system.

Best,

Jiashow

0 Kohsuke Hamasaki over 4 years ago in reply to Jiashow Ho

Hi, Jiashow,

My understanding, the Ser could start up with Internal clock when sync clock is not present.

So the Forward channel should be based on Ser internal clock.

Yes we have AC couple in line. Means we don't have to care about Forward channel transient voltage on RIN pin?

Thanks,

Best regardsd,

Koh

+1 Jiashow Ho over 4 years ago in reply to Kohsuke Hamasaki

HI Koh,

That's correct.

Best,

Jiashow

Interface forum