• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 51 subscribers
  • Views 284 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC2640: Questions about CC2640 ADC module

Michael McCully
Intellectual 375 points

Part Number: CC2640

Hello,
I have some questions about the CC2640's ADC module.
(1) On p.20 of the datasheet (swrs176b.pdf) regarding the 4.3V equivalent reference, is this a real reference, and where is it generated?
(2) On the same page regarding the 1.48V internal reference, it says it is derived from the "scaled value (4.3V) as follows", and then gives the derivation formula.  What does the "scaled value" of 4.3V mean?
(3) On the previous page (p.19), for ENOB test conditions using"Internal 1.44-V reference, voltage scaling disabled, 32 samples average, 200 ksps, 300-Hz input tone", is the 300-Hz tone the input to the ADC, which I presume it is and if so, is it biased at above ground so it would fall within the dynamic range of the ADC which is in this case 1.44V. I am presuming that this 1.44V internal reference establishes the full dynamic range of the ADC. In other words, does the 300 Hz tone have to be centered around 1.44/2 = 0.72 V and therefore it should be biased externally to 0.72 prior to being applied to the ADC input?
Thanks and Best Regards
  • 0
    TI__Guru** 106705 points
    Hi Michael,

    You can find more details in the ADC chapter in www.ti.com/lit/pdf/swcu117

    1) Note that is says "equivalent" and also read footnote 2). The reference is actually 1.48 V, but the input signal is scaled.
    2) I agree that the text could have been more clearly formulated. The formula is actually the input signal scaling when using the 4.3V reference.
    3) That is correct.

    Regards,
    Fredrik