ISO7741-Q1: What's the pin status when there are no signals

Ted Zhang

Intellectual 2280 points

Part Number: ISO7741-Q1
Other Parts Discussed in Thread: ISO7741

HI Team,

What's the default output pin status when there are no signals present in input, is it high/low/ Hi-Z?

Thanks

over 3 years ago

0 Manuel Chavez over 3 years ago

TI__Genius 17100 points

Hi Ted,

Thank you for posting to E2E! When no signal is present on an isolator’s input channel or power is disconnected on the input side, the channel output will continuously output its default state. Outputs would be continuous LOW for “-F” suffix devices like ISO7741F and continuous HIGH for “non-F” suffix devices like ISO7741.

Please let me know if you have additional questions.

Thank you,

Manuel Chavez

0 Ted Zhang over 3 years ago in reply to Manuel Chavez

TI__Intellectual 2280 points

HI Manuel,

Thanks for your reply. Do we have isolator that can output HI-z in default?

Thanks

0 Manuel Chavez over 3 years ago in reply to Ted Zhang

TI__Genius 17100 points

Hi Ted,

Digital isolators with EN pins, including ISO7741, can output Hi-Z when the output side of the isolator is powered up and EN = LOW. Our digital isolators do not presently output Hi-Z as a default state since data transmission would be interrupted. What is the use case for Hi-Z here?

Respectfully,
Manuel Chavez

0 Ted Zhang over 3 years ago in reply to Manuel Chavez

TI__Intellectual 2280 points

HI Chavez,

One more question, can they keep turn on and off the Enable pin at a certain frequency, like every 5ms frequency? Any risk on this?

They want to reuse the SPI, and can they tie the enable pin with CS(the period for the CS is around 5ms)?

0 Manuel Chavez over 3 years ago in reply to Ted Zhang

TI__Genius 17100 points

Hi Ted,

There is no problem with cycling EN pin on and off repeatedly, and it is okay to control EN with a signal that is tied to an input pin on the same side of the digital isolator.

Please let me know if this answers your questions.

Thank you,
Manuel Chavez

Isolation

Isolation forum

ISO7741-Q1: What's the pin status when there are no signals