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What is maximum voltage PWM pins can give?

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FYI, PWM doesn't vary voltage at all except going to Vcc and Gnd. It's never in between. –  Annonomus Penguin♦ Feb 14 at 14:46

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Since PWM pins are digital outputs, the maximum output voltage is VCC.

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Or a little less, depending on load. In effect, the PWM maximum at 100% duty cycle is VOH or the high-state logic output voltage, and the data sheet will characterize what that is in relation to Vcc. –  Chris Stratton Feb 13 at 16:36
    
The datasheet itself does not specify a maximum in the tables, but in the charts it gives a maximum of Vcc. –  Ignacio Vazquez-Abrams Feb 13 at 16:43
    
There's a difference between "Maximum that could be seen" (which arguably is more like Vcc+.6v) and "Voltage that will be seen at Maximum duty cycle" - the latter is the same as the voltage of a "1", and that is not necessarily Vcc but rather depends on the load, in a way that the data sheet should at least roughly characterize (ie, voltage at a given source current, effective Rdson, etc). –  Chris Stratton Feb 13 at 16:45
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On a typical Arduino board, PWM pins will theoretically only ever operate at ground (+0v) or Vcc (typically +5v). PWM is a square wave, which means it alternates rapidly between those two values, aka LOW and HIGH.

With that said, if you run it with a 50% duty cycle, then the average voltage over several cycles will work out as 50% of Vcc (i.e. typically 2.5v). The same applies to other percentages. It's important to note that it's not equivalent to a 'true' analog signal though, and shouldn't be used as such.

As a side note, there are some modified Arduino clones which have a voltage selection switch. These typically let the pins operate at either 3.3v or 5v, and should affect PWM (as far as I know).

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