DP83869HM: How the device will work when it detects LOS signal?

Noriyuki Takahashi

Part Number: DP83869HM

Hi team,

How the device will work when it detects LOS signal?

Customer wants to use DP83869HM in 100Base-FX. JTAG_TDI/SD pin is also connected to LOS signal of SFP fiber transceiver.

So they want to understand the behavior of the device when it detects LOS signal. This is because they are worried about LOS signal can be sent to DPS83869HM accidentally.

Regards,

Noriyuki Takahashi

over 4 years ago

0 Gerome Cacho over 4 years ago

TI__Mastermind 39835 points

Hello,

The LOS works as an inverse or active low signal detect. When the communication is established, this signal is kept as a high. When the communication has been lost, this will be pulled low. At that point, the PHY will drop link. I would advise checking with the SFP transceiver manufacturer if the LOS signal would ever be accidently sent.

Sincerely,

Gerome

0 Noriyuki Takahashi over 4 years ago in reply to Gerome Cacho

TI__Genius 10980 points

Gerome,

Thanks. But it seems that there are no description on the datasheet about how the device will work when it detects LOS signal.

Are there any app note about it? or Could you explain the detail?

Customer need it in order to design their system.

Regards,

Noriyuki Takahashi

0 Gerome Cacho over 4 years ago in reply to Noriyuki Takahashi

TI__Mastermind 39835 points

Hello,

If the LOS signal is pulled low when the PHY has a link established, the PHY will drop the link.

Sincerely,

Gerome

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DP83869HM: How the device will work when it detects LOS signal?