UCD90320U: "Ignore input during delay" LGPO feature issue

Hello,

I have made more investigations on this issue.
I have simplified the configuration and change the pinout.
LGPO = GPI with :
- delay = 25 ms
- delay when asserting = ON
- delay when de-asserting = ON
- ignore inputs during delay = OFF

Issue is reproduced when GPI is :
- positive pulse = 2 ms every 25 ms ==> LGPO toggling every 27 ms
- negative pulse = 2 ms every 25 ms ==> LGPO toggling every 27 ms
- positive pulse = 5 ms every 25 ms ==> LGPO toggling every 30 ms
- positive pulse = 2 ms every 12.5 ms ==> LGPO toggling every 27 ms
- positive pulse = 2 ms every 6.25 ms ==> LGPO toggling every 27 ms

Issue is not reproduced when GPI is :
- positive pulse = 2 ms every 20 ms ==> LGPO = 0V
- positive pulse = 2 ms every 30 ms ==> LGPO = 3.3V

I think that the LGPO is working like this :
0/ LGPO = 0 and GPI = 0
1/ detect a rising edge on GPI
2/ activate the delay and don't check GPI during the delay
3/ when the delay expire, check GPI again
4/ if GPI = 1, then LGPO = 1 ; if GPI = 0, then LGPO = 0

According to Ti documentations, LGPO is not supposed to work like this.
Cf : slvuaw9c - UCD90320 Sequencer and System Health Controller PMBus Command Reference.pdf

Any GPI activity that is below the delay should be filtered by LGPO.
But according to my measurement, it does not filter.

I would like to have a proper confirmation from Ti on how the LGPO is supposed to behave.
Is it filtering or not ?

Thanks,
Regards,

Here are some screenshots.

GPI positive pulse = 2 ms every 25 ms ==> LGPO toggling every 27 ms

GPI positive pulse = 5 ms every 25 ms ==> LGPO toggling every 30 ms

GPI positive pulse = 2 ms every 6.25 ms ==> LGPO toggling every 27 ms

GPI positive pulse = 2 ms every 20 ms ==> LGPO = 0V

Hi, Julien,

Can you share the project file (.xml) saved using Fusion GUI so we can have a look?

Regards

Anne Ngo

UCD90320U 3.0.0.3321 Address 119 Project File.xml

Hi, Julien,

The feature is "Delay Time" when asserting/de-asserting, not asserting/de-asserting time. It works as:

When GPI2 is low (0b), then GPO1 will delay a time specified by "Delay Time" which is 50 ms, then GPO1 goes high (1b). GPO1 stay a high as long as GPI2 is low. Whenever GPI2 is high, GPO1 will delay 50 ms, then goes low (0b). => It works as expected.

Anne Ngo

Hello,

Ok, so indeed, this what I have suspected, when the option "ignore inputs during delay" = OFF, the LGPO ignores the change of states of GPI during the delay.

It's only at the end of the Delay that the GPO checks the state of the GPI and, depending on the new status of GPI, GPO states will change or not.

Because when I read the LGPO descriptions and Ti documentations, the function is not supposed to work like this.

It is supposed to do the following : 

1/ GPI changes state

2/ GPO change state after the Delay only if GPI is stable

3/ during the delay, if GPI is not stable, the Delay is reset

It is supposed to work like a Timer Block LTC6994-2 in debouncer mode.

Is it possible to fix this with a custom Firmware patch on the UCD60320U ?

The way that Ti implements this feature today in UCD90320, I don't see the application.

I don't see why customers would use this feature the way Ti is doing it instead of having a debouncer.

Do Ti have example of applications ?

Thanks,

Regards,