what are the maximum and minimum PWM output voltages?

[ferkar]

hi everyone. ı have simple question. when i measure the output of pwm module for %100 duty cycle i get 4.25V dc. why it is not 5v?

could i take an exact 5V output from a PWM module ?


thanks ....

[Ttelmah]

No....
Depends on your load to some extent, and (obviously), what the supply really is at the chip's pins.
Look at the data sheet for the chip. 'Output high voltage'.
Now, your figure is a little low. Suggests either that you have more load on the pin, than the specification is done at, or that the chip's supply is actually a little low. The specification, is normally a _minimum_of Vdd-0.7v at 3mA. In general, a figure more like perhaps 4.5v, is typical, into perhaps 1mA max load.
You can ensure the 'high' is better, by having a pull-up resistor on the output, but this tends to raise the 'low' output level.
Even the best switches, will never actually get to 5v, but using good MOSFET drivers figures closer to perhaps 4.8v, are relatively achievable.

Best Wishes

[ferkar]

these datas are very useful.
thank you indeed.