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In practical industrial applications (regardless of any particular industry), is there any use for a dither module that goes along with a PWM module considering HRPWM's are available. With my limited experience I can justify using the former as it's most likely cheaper than the latter. However, this is a rather weak reason, and I was hoping someone can share their experiences/thoughts on the usefulness of dither?

My intention is to keep this question as far as possible from being opinion-based or too broad, but just to make sure - I am looking for an extended 'yes' or 'no' answer to whether a dither module may be useful in practical applications.

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  • \$\begingroup\$ what does dithering have to do with enabling a finer PWM? \$\endgroup\$ Commented Feb 3, 2016 at 4:00
  • \$\begingroup\$ @hassan789 Please correct me if I am wrong - I still may be getting some terminology mixed up. My impression was that dithering allows to adjust PWM duty cycle/period on a sub-LSB level, i.e. 1/2 LSB, 1/4 LSB, etc. Is this what's called finer resolution? \$\endgroup\$ Commented Feb 3, 2016 at 5:53
  • \$\begingroup\$ I now see what you mean. \$\endgroup\$ Commented Feb 3, 2016 at 16:44

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Lower cost is hardly a weak reason.

Using a more expensive part than necessary, without good reason, is hardly a mark of a good design, and specifying a high-res type may constrain the design in other ways (for example, forcing the designer into a vendor with inferior pricing, availability or performance).

Power consumption may be less too, though it's probably not a huge difference overall.

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  • \$\begingroup\$ Good comment - thank you! It seems like dithering is just a quick-and-dirty solution to achieving a little bit of extra resolution on PWM but not necessarily useful when it comes to serious applications? Is it so? \$\endgroup\$ Commented Feb 3, 2016 at 16:20
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    \$\begingroup\$ No, not so. Just because it's a serious application does not mean it needs to use the very finest available technology. It just needs to be good enough. Anything beyond that is 'gold plating' and is very bad engineering (and project management) practice. Meet the specifications and it's perfect. Don't meet the specs and it's a fail. I have $10,000 instruments that use 8-bit DACs. No need for any more in the particular place where they're used even though a 16 bit DAC might look more impressive- they work just as well from the application point of view. \$\endgroup\$ Commented Feb 3, 2016 at 16:23
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    \$\begingroup\$ Dithering introduces subharmonic noise, i.e. noise at frequencies below the PWM frequency. Filtering this noise means a lower cut-off frequency of the low-pass filter, which slows down the response and might result in higher capacitor costs. If this is no issue, dithering is a perfectly valid design approach. \$\endgroup\$ Commented Feb 3, 2016 at 17:14

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