• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 52 subscribers
  • Views 471 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.

Original question:

why cc2541's frequency can reach 2496MHZ

CC2541: Internal Frequency Oscillator

Udhayakumar Mahendiran
Prodigy 240 points
Part Number: CC2541

Hi,

In CC2541 datasheet I found that it is having two internal oscillators, one is 32Khz RC oscillator and 16MHz RC oscillator. If it is having internal oscillators what is the need for external oscillators. can anyone elaborate when and where internal and external oscillators has to be used? 

  • 0
    TI__Genius 9215 points
    Hi,

    This has to do with accuracy. An external oscillator using a XTAL (or TCXO) have typically much better accuracy than an internal oscillator (RC or similar). The oscillator accuracy is what sets your RF accuracy so when doing RF you typically need much better accuracy than what a internal oscillator gives you.
    You can find numbers on this in the CC25431 datasheet. Example from the CC2541 EM reference design: 16-MHz RC oscillator have ±6000 ppm accuracy when it's calibrated while the 32-MHz Crystal oscillator have ±40 ppm accuracy.

    Best Regards,
    R.M
  • 0 in reply to R.M
    Prodigy 240 points

    Hi ,

    Thanks for the explanation. So I can use internal oscillator instead of external crystal , right? (if accuracy is not I'm worried about) . Will it work?

    One more question, for a power constrained application which will consume very less power, a)Clock using external 32Khz crystal , b)Clock using internal 32Khz oscillator..? 

  • 0 in reply to Udhayakumar Mahendiran
    TI__Guru** 106705 points
    There is no noticeable difference in current consumption between the various oscillators.

    You can use the internal oscillators if accuracy is not important to you, but the radio will not run without the 32 MHz crystal oscillator (it does not work with the internal high frequency RC oscillator).

    Regards,
    Fredrik