Low Voltage Warning interrupt doesn't trigger at configured trip point. Kinetis MK02FN128VFM10.

[matthewking]

I am using the LVW interrupt in register PMC_LVDSC2 to quickly identify brown-out/power down scenarios.

I am using the "Low-voltage warning thresholds — high range", and have tried each of the 4 possible trip points within the high range: 2.7V, 2.8V, 2.9V, 2.3V. 

The microcontroller does detect the low voltage event, but always at 2.38V (+/- .02V), regardless of the configured trip point. I know this because I toggle an I/O pin when the ISR fires, and I see the supply voltage to the MCU at the time the I/O toggles.

Is there a known errata on the LVW interrupt trip point voltage?

[Robin_Shen]

Hi Matthew King,

I didn't find related errata in KINETIS_K_0N36M.
Please refer the answer in: mk60dn512 low voltage warning
Would you please modify the codes and test it on your board.

Best Regards,

Robin

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[matthewking]

Hi Robin.

While the suggested code in the link you sent didn’t actually change the behavior, it did trigger a thought about how I was using the LVD/LVW control registers.

I had the LVD set to the low voltage trip - low range, but intended to use the low voltage trip – high range for the LVW.

I reconfigured LVD to use the high trip range, and it is now working as expected.

Thanks,

Matt