PCA21125 output is not turned active right away

[StrongOrange]

Hi,

I am trying to use PCA21125 and have a question.

Is there a delay to turn PCA21125 output active?

My current use case is like this.

Case: Set "alarm time" to "current time" in order to set PCA output active "immediately"

When I do this, I receive Rx (AF = 1, AIE = 1) properly and consider this output is active straight.

However, there's a delay for output active.

When I set alarm time to current time, I also trigger another digital output and compared both.

Even though digital output level was changed, pca21125 output changed much later, there was 500ms delay between them.

Is it normal behavior?

[StrongOrange]

I was understanding it correctly.

Let's say 

Current time: hour 3 minute 15.  AEN H AEN M enabled. And AIE enabled.

- I set alarm time to hour 3 minute 15.

AF becomes active but its output pin haa 500ms delay to become active and changes its level.

[diazmarin09]

Hello StrongOrange, 

As far as I know, this is not the expected behavior.          

Could you please perform the following test? I mean, enabling the minute alarm only?

Could you please share your schematic?

Regards,

David

[diazmarin09]

Hello StrongOrange,

I hope all is great with you. Thank you for using the NXP communities.

I would like to share with you the following statement that might be useful:

Please note that when the Minute_alarm (address 0x09) is set to 0x05, it means that the alarm will be triggered when the actual time from the RTC’s minutes count is equal to ‘05’, it does not means that it will be triggered 5 minutes after you make this setting.

For example, if you set the ‘05’ minutes alarm at the time 10:15:20 (hour 10, minute 15, second 20), it will take 50 minutes to fire the ‘05’ alarm (at actual time 11:05:50). It will NOT fire at 10:20:20 (05 minutes after the alarm is set).

Based on the statement below, is that the expected behavior of your configuration?

I hope this information helps.

Regards,

David