• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 49 subscribers
  • Views 163 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA228: integrated current sensors: how to disable out-of-limit alerts?

Vlad Blanshey
Intellectual 690 points
Part Number: INA228
Other Parts Discussed in Thread: INA237, INA238,

Hello, this question is for any INA type of integrated sensors: INA228/INA238/INA237.

I need to find out how to enable / disable any specific ADC results comparison from triggering an ALERT (meaning both as a flag in ALRT register and active ALERT pin output).

The DIAG_ALRT register has bit-flags for each out-of-limit event . These flags are both read-write capable. The meaning of "read" operation is obviously to read the flag status but description does not specify what is the case for "write" operation. For ex. Ch. 7.3.7 of INA228 datasheet  says "diagnostics listed in Table 7-1 are constantly monitored" meaning that there is no setup to enable/disable any particular ALERT event. The only way to disable any particular alert as I see it is indirect by keeping the extreme default values in any out-of-limit register. For example if I keep the BOVL register (Bus Voltage Over Limit) value default 0x7FFF then probably Alert will never trigger. Or can it fire ALERT if it reaches that extreme value?

What is the intended case for possible writing to the respective bit-flags of DIAG_ALRT register? If they are not for the configuration of the ALERT events, neither they are for clearing after alert (this is done automatically when reading DIAG_ALRT register) . So what was intended purpose to write in there? Am I missing something?

Vlad

  • +1
    TI__Genius 17990 points

    Hello Vlad,

    I just did some testing on the EVM, and writing to the DIAG_ALRT did clear the flag for me (when in latched ALERT pin mode. I tested on the temperature over limit register). So, I believe these are specified as R/W registers because either read or write operation will clear the flag. I've made a note to the datasheet team to see if we can get this clarified there. 

    I also used the EVM to test if the ALERT would trigger if the limit was set to the the default extreme value. Specifically, I tested the shunt over voltage threshold.  When set to 0x7FFF the ALERT did not trip even with a very high voltage on the pins.  It did trip the ALERT when set to 0x7FFE. So, it seems that the voltage needs to cross the threshold to trip the ALERT, so the ALERT cannot be tripped when set to the extremes because the result register can't fit a value outside of that extreme. So, essentially, the default extreme values are "off" for the ALERT, and you would need to set them to some other value to enable the ALERT.

  • 0
    Intellectual 690 points

    Thank you Mitch. Good to confirms that the extreme threshold settings cannot trigger the alert. Would be helpful for developers to have this clearly mentioned in the datasheet that this is intended way to turn off the alert for any ADC result.

    Now it's clear that the writing to the DIAG_ALRT bit-flag can clear the flag in ALATCH mode just the same way as reading the flag (the very purpose why all the bit-flags are there) , so in essence any such writing is useless (this confused me when reading datasheet).

    My PCBs for these chips are coming in few days, I am yet to assemble and test them but the extend of integration in this small package is mind blowing! I was dreaming this for years to have the precision OpAmp on the same chip with ADC and all supporting components (and I need at least 85v bus!) but didn't believe it can be within my lifetime...apparently TI heard me...

    Great job! Thank you.

    Vlad

  • 0 in reply to Vlad Blanshey
    TI__Genius 17990 points

    Vlad,

    Glad I could help! Yes, the INA228 is really a great part!  I'll send your feedback about the datasheet to the datasheet team.