MPC5646C adc reference voltage

[robinauriol]

Hello,

I don't understand how adc voltage reference works on this microcontroller family.

Is there an internal voltage reference made with the input voltage on VDD_HV_ADC0 pin or do I have to use an external voltage reference and put it on VDD_HV_ADC0 pin?

It is said in the datasheet that Vdd_ADC0 has to be equal to VDD_HV_A +/-0.1V. But if it is the case, i can't use an external reference voltage. For now i have connected all the supply pins to the same voltage (5V). But the accuracy of the 5V is about 2%, wich is the total accuracy i need on my measures !

Thank you for your time.

Robin

[davidtosenovjan]

One note about recommended ferrite bead:

[rkandiah]

davidtosenovjan‌, could you please share the document above you have taken the screenshot from? I cannot seem to find this in any of the hardware design guides I found online. I would like to reference it for any other design guidelines. 

Thank you.

[davidtosenovjan]

Unfortunately the document is confidential and I cannot share it with you.

[davidtosenovjan]

Hi, I am afraid that this device does not have separated ADC voltage reference and ADC power supply, you apparently cannot use different power rails and it must me derived from one source.