ADC conversion precision

[pauvilanova]

Hi, I'm working with the MKE04 with the ADC conversion. I'm reading  the signal from a linear potentiometer and I'm trying to differ 100 positions, in this case (0-5v).

The thing is that the ADC conversion is not stable, for example working with 8 bits I get +-4 conversion value when the potentiometer is not moving. I've tried with everything that I know of ( hardware filtering, software average) and I could not get beyond that -+4 value. Then I tried with other board that we have the MKV11Z64 having the vrefh at 5v and the conversion is far better, with just 1 value of error.

The thing is that I cannot use the MKV11 for this project because we are out of space we would like to use a tsop16 micro at best, so I have two questions.

Are there any tsop 16 or less microcontrolers specialised on ADC?

If not, is there any way to improve the adc conversion of my uc?

Thanks

[jingpan]

Hi Pau,

KE04 ADC shouldn't be so bad.I think you can

1. check VDD power supply. Is there ripple?

2. check Ras/Cas(Figure 16 in datasheet)

3. Please try the ADC example in KE04 SDK to see if the problem caused by hardware or software.

There are some articles shows how to improve adc performance. You can also take a look.

https://community.nxp.com/docs/DOC-104288 

AN5250

AN4373

Regards,

Jing