I am was wondering if an IC like the PCA9685(Datasheet) that generates PWM signals can be used in a PID controller for controlling a heated bed on a 3D printer.
My understanding of PWM is that it will be to fast for a normal relay but that it might work with a Solid State relay.
Even if it can bring down the number of times I have to check the Temperature it would be useful.
Best Answer
PWM can and is used for PWM controlling, especially in Switched Mode Power Converters where the switches are usually MOSFETs which makes conductive losses in the switches very low.
The function of PWM in the circuit is to convert the control signal from the PID (for example) into a switching signal. PWM is constant frequency variable duty-cycle. You have several choices other than PWM for converting the control signal to a switching signal e.g Constant On-Time (Variable switching frequency, fixed on-time), Constant Off-time etc..
You also have several control strategies other than PID, e.g. i) threshold :error pos/neg triggers a COT pulse; ii) Hysteretic : Switches ON below lower setpoint threshold and turns OFF above upper threshold etc..etc..
The type of IC you selected seems like overkill for the application. Switching converters are more suitable for your application I'd say, and can be bought in IC form, designed with op-amps/comparators (see below) or a Micro-controller with PWM capabilities + associated MOSFETs and MOSFET drivers.