Hi, in one part of my project, I'm switching an N channel mosfet via digital pin PWM. It's adjusting power from two 3.7v batteries in series to a load. I need to be able to read the average voltage on the load side, but it's pulsing. I'm trying to figure out what the best way to achieve this is. Thanks!
It's a resistive load being powered by batteries. I'd really like to get the actual voltage somehow, since battery sag/voltage drop will play an issue. I found more info here.
Yes, if he doesn't know the difference, isn't it important to educate him about that difference? Perhaps he says average in his message, but really wants to know the RMS, but doesn't know until he finds out what RMS voltage is.
I need to be able to read the average voltage on the load side,
My apologies, RMS and average are -not- the same thing here.Average voltage is just.. an average of the voltage. If 5V is On 25% of the time, the average voltage is 1.25V. Whereas the RMS voltage would be 5*(0.25^0.5) = 2.5Vrms. IE, the voltage that would cause the same power dissipation in the load as 5V that is on 25% of the time.
I think the averaging of the PWM pin using the LP filter accurately reflects the averaging of the power applied to the motor load.
vffgaston is right, power is not proportional to voltage. Hence all my futzing about to calculate RMS voltage.