How to use lmt70 with nrf51

RE: How to use lmt70 with nrf51

Ole Bauck — Thu, 22 Dec 2016 08:15:56 GMT

That small error could be many things. The multimeter could be inaccurate. The impendance of the circuit may affect the ADC measurements, especially if you have a multimeter connected while you are doing measurements with the ADC.

For increased accuracy you can also try to use the crystal as the clock source instead by starting it before the measurements. Inaccuracies in the clock may lead to inaccuracies in the measurements.

You may also have an offset error which can be up to 2% according to the Product Specification.

RE: How to use lmt70 with nrf51

IlyaM — Wed, 21 Dec 2016 14:13:17 GMT

Yes, you are absolutely right. I already fixed my code. But, btw, my multimeter shows 10 mV more than ADC. Is it ok?

RE: How to use lmt70 with nrf51

Ole Bauck — Wed, 21 Dec 2016 12:40:10 GMT

The read value is from 0 to 1023 for 10 bit ADC, it is not corresponding to millivolt measured. If you read 801 from the ADC, then this equals

801/1023 * 1.2V ~= 940mV

When using 10 bit resolution and VBG (1.2V) as voltage reference. According to the datasheet this is just over 20 degrees, which should be about correct (right?).