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C2000 Resolution loss in bits

Bard Ciou
Intellectual 900 points

Hi All

May i know how can i get the resolution loss in bits as below table?

Any formula is useful, thanks.

  • 0
    TI__Mastermind 27200 points

    Hi Bard,

    The table shows the number of bits by which PWM resolution is degraded when only part of the duty cycle is used.  For example, taking the upper left entry, only (0.8 / 14) * 100 = 5.714% of the available duty cycle is being used.  To express this in binary bits, we take the base 2 logarithm of (0.8 / 14) = -4.1293, or approximately 4.1 bits of lost resolution.

    In other words, if you had 16 bits of PWM resolution over 100% of the duty cycle, only using 5.7% of the duty means you have 16 - 4.1293 = 11.87 bits of resolution.

    You can convert between logarithmic bases like this: log_a(x) = (log_b(x) / log_b(a))

    As the slide says, this lost resolution compounds the effects of poor PWM resolution at high switching frequencies which can lead to limit cycle issues.

    Regards,

    Richard