TLK110: Link pulse was returned under power off state

Toshi

Expert 1780 points

Part Number: TLK110
Other Parts Discussed in Thread: TLK111, TLK105L, TLK106L, TLK100, TLK105, TLK106

Hi,TI,

I detected a strange behavior of TLK110.

Under power off condition of TLK110, when a cable was connected between TLK110 and a HUB,

the HUB(power on) send a link pulse to TLK110(power off), at that time,

TLK110 send a link pulse back to HUB, even if the device was power off .

The returned link pulse was about 300mV peak voltage.

A problem is that some HUB detected the returned link pulse and hung up.

Did you detect the behavior before ?

Please let me know why the device send back a signal to HUB even if it has not power supply ?

over 7 years ago

0 Ross Pimentel over 7 years ago

TI__Mastermind 23675 points

Hi Kobayashi,

Do you have a common mode choke between the IC and the transformer?
A CMC is needed to prevent the reflected wave from linking to the partner when the device is powered-down.

Kind regards,
Ross

0 Toshi over 7 years ago in reply to Ross Pimentel

Expert 1780 points

Ross, thank you very much for your help.

I see, TLK110 needs CMC in order to prevent the reflection.

Well, Does the TLK111 also need CMC ?

Thanks and Best Regards,

Toshi Kobayashi

0 Ross Pimentel over 7 years ago in reply to Toshi

TI__Mastermind 23675 points

Hi Kobayashi,

All TLK devices need CMC.
TLK105, TLK106, TLK105L, TLK106L, TLK100, TLK110 and TLK111

Kind regards,
Ross

0 Toshi over 7 years ago in reply to Ross Pimentel

Expert 1780 points

Ross, thanks a lot.

I see, these device must have CMC in order to skirt the problem.

If possible, we need a application note or technical document about this, in the future.

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TLK110: Link pulse was returned under power off state