BQ78350-R1: Technical reference Keyin section

Hi JPAlleyne,

It seems that per the TRM the KEYIN can be configured to be an active HIGH or active LOW. Depends what you set the KEY_POL register to. It seems that the only way to turn on the DSG FET ON is to have KEYIN pin experience a transition from HIGH to LOW or LOW to HIGH.

thanks

Miguel

Hi JPAlleyne

I noticed that you rejected the answer, sorry i could not answer your question. Can you please rephrase your question a different way, perhaps?

Thanks

Miguel

Hi Miguel, thanks for responding. Yes, I saw that in the TRM. It's just that specific paragraph that seems to be a bit strange to me... The whole paragraph reads :
"When [KEY_POL] = 0 (active low) and the KEYIN input is low, then the bq78350-R1 operates normally.
However, if KEYIN were to transition to a high state and remain in that state for KEYIN Time, then the
bq78350-R1 would control the companion AFE to turn off the DSG FET. If the KEYIN input transitions
back to low before KEYIN Time expires, then the bq78350-R1 continues to operate normally and the
bq78350-R1 is not influenced by the KEYIN pin.
If the KEYIN input transitions back to a low state and remains in that state for KEYIN Time, then the
bq78350-R1 would control the companion AFE to turn off the DSG FET only if all other safety conditions
allow."

So if we assume that set KEY_POL to 0 so it's active low. The TRM says that if we pull KEYIN high for a certain amount of time (KEYIN Time) then the DSG FET will turn off. The last part confuses me because I would assume that if KEYIN is pulled low for KEYIN Time then the DSG FET should turn "ON" not OFF right?

The TRM says that "If the KEYIN input transitions back to a low state and remains in that state for KEYIN Time, then the bq78350-R1 would control the companion AFE to turn OFF the DSG FET only if all other safety conditions allow."

Thank you for clarifying this and for the extra information, WM5295.

Take care,
JP