[ TPS2546 ] Short Pulse on D+ after enabling

Kenichiro

Other Parts Discussed in Thread: TPS2546

[ TPS2546 ] Short Pulse on D+ after enabling

Hi, my customer has reported me that short pulse can be seen on DP_IN line after approx.1.2ms from enabling TPS2546. Please see the set up as below.

On this test bench, customer toggles EN pin to switch device mode betwee enable and disable. What customer has observed here is, after almost 1ms from toggling EN to high, short pulse with 0.8V can be seen on DP_IN line. See waveform below. (5V supply voltage for IN pin is on during this.)

When I checked TPS2546EVM with my windows PC, the wavefrorm is not like this. Have you seen this before? It's greatly appreciated, if you can let me know the reason why this happen. Also can you reproduce the waveform at your side?

Thanks,

Ken

over 10 years ago

0 Aleksandras_Kaknevicius over 10 years ago

TI__Genius 15780 points

Hi Ken,

This device falls under the Power Interface team. I will go ahead and move this post to their forum.

Regards,

Alek Kaknevicius

0 Kenichiro over 10 years ago in reply to Aleksandras_Kaknevicius

Mastermind 9165 points

Thanks for your support, Alek.

I wait for update from team!

Regards,

Ken

0 Milo Zhu over 10 years ago in reply to Kenichiro

TI__Intellectual 2795 points

During toggle EN, is there protable device attached at the USB port? Becuase maybe portable devcie would do some BC1.2 primary detection and send out a 0.6V pulse on DP, you can check BC1.2 specificaiton to see this behavior.

0 Kenichiro over 10 years ago in reply to Milo Zhu

Mastermind 9165 points

Hi Milo,Thank you for your reply!
No, they have no portbale device attached during this test, just enabling / disabling device with EN pin.
Have you seen this before?Thanks,Ken

0 Kenichiro over 10 years ago in reply to Kenichiro

Mastermind 9165 points

Hi Milo,

Would that be possible for you to try to reproduce customer behavior with TPS2546EVM? When I checked, I have seen small negative pulses on both DM_IN/DP_IN TP, and it was not same as customer behavior.

TPS2546EVM

plug into PC USB poart
Leave open USB PD side
toggling EN from external power source (remove R12/100kohm resistor from EVM)
Monitor data pins

It's greatly appreciated, if you can double check.

Thanks,

Ken

0 Milo Zhu over 10 years ago in reply to Kenichiro

TI__Intellectual 2795 points

Ken,

FIrst, i want to know, is there any influence for customer's design or application for the pulse?

0 Kenichiro over 10 years ago in reply to Milo Zhu

Mastermind 9165 points

Hi Milo,
At this moment, customer is looking for the reason why this short pulse happen,
so I would like to ask you whether you know something, or possible to reproduce their behavior.
Thank you for your support in advance.Regards,Ken

Power management

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[ TPS2546 ] Short Pulse on D+ after enabling

[ TPS2546 ] Short Pulse on D+ after enabling