ADC registering too high values

[oles]

I am using LMT84 temperature sensor directly connected to P06 on my nRF24LE1, QFN24. Using the built-in BG reference of 1.2V, I measure temperatures from about -30C up to 85C.

The circuit is battery driven. I use 10bit adc, 12us T_ACQ, logging every 10seconds or rare. The voltage from the sensor is accurate, it is measured with oscilloscope and multimeter.

However, the ADC is measuring some values too high. It is a little difference between the two circuits I am testing on; one shows 33mv too high (measuring 958mV), the other approx 20mV too high (measuring 945mV). The voltage shall be 925mV. As far as I read both datasheets, there are no need for a buffer between the sensor and the ADC.

Any ideas for further fault finding?

[oles]

Thank you. I have been looking into these posts, and some other too. Just havent clearified the problem yet, I will give it another try.