Deviation in Board Power Supply (V_BRD) & AFE Channels

RushinMehta — Mon, 03 Jul 2023 07:48:50 GMT

Hello All,

I have 3 Dev-kits (TWR-KM35Z7M), in all of them the V_BRD power net which is said to be 3.3V [Both in SCH & in the datasheet of the IC used NCP1117ST33T3G (U2)] is measured to be 4.1V.

Even in the BRD file, the net says P3V3. But our Test equipment show it to be 4.1V.

So, can this cause any issues in the AFE Channels & their Voltage references as they are connected directly?

We are developing an Energy Meter & we are facing an issue that when I give a Sine wave to AFE Channel 0 & another phase shifted sine wave to AFE Channel 1,channel 0 saturates, even if the pk-pk is below 400mV (500mV is the range of AFE channels).

Also when we give the same waveform for AFE Channel 2, it does not saturate !

Is this due to improper Voltage reference or is this something else?

Re: Deviation in Board Power Supply (V_BRD) & AFE Channels

RaRo — Thu, 13 Jul 2023 17:33:05 GMT

Hello @RushinMehta,

Just for double check, this behavior happens only on AFE Channel 0?

Have you tried using the SDK's examples configuration for AFE Channel 0? You could use the afe_interrupt example configuration and test the behavior of the AFE Channel 0.

Finally, could you please try reducing the voltage of the sine wave? Does it stop saturating with any pk-pk voltage?

Best regards, Raul.

topic Deviation in Board Power Supply (V_BRD) & AFE Channels in Kinetis Microcontrollers

Deviation in Board Power Supply (V_BRD) & AFE Channels

Re: Deviation in Board Power Supply (V_BRD) & AFE Channels