CC2640R2F: CC2640R2F ADC issue

Big Bill

Expert 1980 points

Part Number: CC2640R2F

Dear All:

I used the CC2640R2F to measure the voltage that it's accuracy is 0.5 mv., can you help tell me how to measure so accuracy voltage? Can the CC2640R2F ADC resolution support it

Look forward to your reply~thanks

over 9 years ago

0 Fredrik K over 9 years ago

TI__Guru** 106705 points

Hi Bill,

The ADC performance data is listed in the CC2640R2F datasheet. ADC driver example is found here: dev.ti.com/.../

Cheers,
Fredrik

0 Big Bill over 9 years ago in reply to Fredrik K

Expert 1980 points

Dear Fredrik:

Thanks for your reply. I don't think the CC2640R2F ADC precision can support the 0.5mv accuracy . what is your advice

0 Fredrik K over 9 years ago in reply to Big Bill

TI__Guru** 106705 points

If you cannot get the desired performance from the internal ADC you need to use an external device with higher precision.

0 Robert Chen over 9 years ago

Mastermind 9135 points

Hi,

To measure very small signal, you will need to add an OP amplifier before ADC.

0 Big Bill over 9 years ago in reply to Robert Chen

Expert 1980 points

Hi Robort:

The analog signal is not small, the 0.5mv voltage is the resolution ratio.

0 Robert Chen over 9 years ago in reply to Big Bill

Mastermind 9135 points

What is the voltage range of the signal?

The effective number of bits (ENOB) of ADC is 11.1 bits when internal 1.44V reference is used. So, the full-scale range is 2^11.1 - 1 ~= 2194. 1.44V/2194 = 0.656 mV, this is larger than the required 0.5mV precision.

So, you have two ways to go:

1. Add an external amplifier to magnify the analog signal at first.
2. Use over-sampling to increase ENOB.

0 Big Bill over 9 years ago in reply to Robert Chen

Expert 1980 points

Dear Robert:
Thanks for your relay. i think it is better for us to use over -sampling to increase the ENOB

Bluetooth®︎

Bluetooth forum

CC2640R2F: CC2640R2F ADC issue