CC2540 ADC reference voltage

Parth Dholakiya

Other Parts Discussed in Thread: CC2540

Hello,

I have connected a potentiometer to AIN4 pin(port0_4) of CC2540. I have taken internal reference voltage i.e. 1.24V. ADC resolution is 14 bits so max ADC count will be 8191.

According to me i should get max ADC count at ~1.24 V but i am getting max ADC count at 1.28V.

can anyone please tell me why this is happening?

Thanks in advance!

over 11 years ago

0 TER over 11 years ago

TI__Guru**** 317180 points

Have you calculated the external components according to the attached?2330.External component sizing.docx

0 kong lei over 11 years ago in reply to TER

Prodigy 20 points

I use the resistive ladder to divide down the battery voltage below the internal reference.The value of the resistive ladder is 100K and 200K. I use AVDD which is 3.3V as the reference voltage and the resolution is 14 bitThe voltage that is input to the ADC is 2.8V, but the ADC result is 5230. It is much more smaller than expected. What's the problem? Is the value of the resistive ladder too small? Tank you for your help!

0 kong lei over 11 years ago in reply to kong lei

Prodigy 20 points

Can you mail me the full 2330.External component sizing.docx? Some tables and figures are missed, thanks.

0 TER over 11 years ago in reply to kong lei

TI__Guru**** 317180 points

The document is complete. The references are not fully updated, the table is table 6.3 referred to. Do you use a decoupling cap? Have you tried to calculate what you need according to the equations stated in the document?

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CC2540 ADC reference voltage