TXS0108E: TXS0108E output issue - output pins not consistent in level shifting

Marcel Hecko

Part Number: TXS0108E

Im having a strange issue with TXS0108EPWR

I do have a following sonncetion of the mentioned part:

The strange thing is, that on pins A4 and A6 Im having the proper 3v3 -> 5v output, but on the A5 the inout (checked) is the same as for A4 and A6, but the output on the B side is 0.3V for high and goes below 0V for low with - see the following image (taking about the last line)

First line of image is proper B output on A4, second line is the input for A5 and third line is the output for B5

The connection is absolutely the same. I have also replaced the TXS0108E and the result is the same.

Any ideas? Leads? How to debug this situation?

Thanks,

Marcel

over 6 years ago

0 Nicholas Mariani9 over 6 years ago

TI__Intellectual 2100 points

Hey Marcel,

Would you be able to upload the images again as PDF or some image file not from dropbox? You can use the insert image in the thread tools when posting. It's getting flagged and can't open them to take a look.

Thanks,
Nick

0 Marcel Hecko over 6 years ago in reply to Nicholas Mariani9

Prodigy 80 points

I have updated my question. Thanks.

0 Nicholas Mariani9 over 6 years ago in reply to Marcel Hecko

TI__Intellectual 2100 points

Hey,

Thanks for the upload, could you tell me what type of signals or protocols these signals are? Also, do you have any loading on the pin in question that isn't present on the others?

Nick

0 Marcel Hecko over 6 years ago in reply to Nicholas Mariani9

Prodigy 80 points

Hi Nick,

I have been trying to use I2C, however the situation also happens when there is no load on the lines at all (e.g. using simple gpio set/clear) (the socket on the left disconnected).

The pin in question is connected to NRF51 - pin 13.

Marcel

0 Emrys Maier over 6 years ago in reply to Marcel Hecko

TI__Guru* 96591 points

Hi Marcel,
The signal on B5 looks like a capacitively decoupled signal. Where are you measuring it? I would recommend measuring directly at the pin of the TXS0108E. It's possible that there is a crack in the trace on your PCB or there might even be a poor connection due to a cold solder joint.

0 Marcel Hecko over 6 years ago in reply to Emrys Maier

Prodigy 80 points

There was indeed a crack in the trace! Not a cold joint.

Thanks for an amazing analysis and a spot on problem definition!

Sorry for such a long wait for a reply - the crack has been found the very day you have suggested a search for it.

Sincerely,

Marcel

0 Emrys Maier over 6 years ago in reply to Marcel Hecko

TI__Guru* 96591 points

Thanks for letting me know Marcel - too often I find myself closing a thread having no idea if it was resolved :)

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TXS0108E: TXS0108E output issue - output pins not consistent in level shifting