Regarding the digital input of AD4697

Hi UBOTI ,

Here are the things you need to take note of:

• Input pins - SCK/SDI/CS/CNV/RESET - have ESD diodes connected to IOGND.
• Output pins - SDO/GP0/GP1/GP2/GP3 - have ESD diodes connected to both VIO and IOGND

May I know the reason why you have asked the correlation of ESD diodes and the digital lines? What do you mean by different from your 2nd point? Also, what is your specific application?

Thank you and regards,
Jo

Thank you for answering.
Let me confirm one last thing.
Is it okay to connect to a 3.3V driven MCU and communicate via SPI with VIO=1.8V applied? (SCK/SDI/CS/CNV/RESET H voltage is 3.3V)

Hi UBOTI ,

I am currently in contact with the product owner. And we are currently working on this. On the other hand, how did you determine that your device has been destroyed?

Thank you and regards,
Jo

Thank you for contacting me.
Device destruction
・When I looked at the BUSY pin, BUSY did not go high even if I set CNV to high. (Even after resetting and changing the setting to output BUSY to the terminal, it remains low)
- Even if I read the vendor ID (address 0x000C), the value is 0xFF and the result is not correct.
Based on the above, it has been determined that the device has been destroyed.

The cause of the destruction is probably when the 1.8V (VIO and VDD) power is not turned on.
I think the cause is SPI communication and applying 1.8V to the GPx terminal from the MCU, so I am not concerned about this at the moment.

However, since I was using the RESET terminal with 3.3V drive, I would be in trouble if there was a cause other than 1.8V not being applied, so I inquired.

Hi, UBOTI .

For the GPx pins, please refer to the absolute maximum rating of Dout. Meanwhile, if your MCU is driven by a 3.3V logic, then your SPI lines should also be driven by a 3.3V. Likewise, if MCU is driven by 1.8V, then your SPI lines should be driven to 1.8V.

Regards,
Jo

Thank you for answering.
Since the maximum absolute rating of VIO is 2.1V, does this mean that it cannot be used as a 3.3V MCU?

According to the digital input specifications in the data sheet, the H voltage can be input up to MAX3.6V, a value higher than VIO.
In what cases can this benefit be taken advantage of?
It would be helpful if you could give me some examples.

Hi UBOTI ,

If I understand your query correctly, you are using/creating a custom board, right? I would suggest using a level shifter or a level translator so a 1.8V SPI line will be able to communicate to a 3.3V MCU. 

Regards,
Jo

Since level shift is a suggestion, is it okay to do without it?
Do I also need to level shift the CS and RESET pins?
Since it is possible to input up to 3.6V, I think it is not necessary.

Isn't it okay to use only SDO for level shifting?

Hi UBOTI ,

Sorry for the late response. I would suggest that all digital lines will be put to the level translator. You can try contacting me through my email if you still have concerns.

Thank you and regards,
Jo