I am designing a digital board which will drive a very coarse (simple on-off) high[er] current speaker. I am worried that the switching of the speaker will cause noise in the power supply driving it. If this was the same power well as the microcontroller, that wouldn't be good.
I will use separate ground and power planes for the power to the amplifier circuit. I don't want to actually use a separate power supply for it's power plane, but think a simple filter might work better. Could I just put an inductor/choke between the "main" power plane and the amp's power plane? I envision with the capacitor, this would essentially form a low-pass filter.
Does this make any sense? Any considerations I should take in selecting values? What about even doing anything in board traces/geomentry to make a simple/crude inductor or provide other isolation?
If I were really concerned about this – I would use a separate power supply. I haven't built the circuit yet and am not seeing any specific problems, so I am just trying to sort of minimize any potential problems. Thus, doing a simple isolation as such might just be a quick and easy thing to do.
Any good tips?
Best Answer
The current transients mentioned, depending on magnitude and how well the amplifier circuit is decoupled, may cause dips in Vsupply as described.
Some points to address for a solution: