crutschow and Klaus here is the reason I didnt use a non inverting opamp:
Simulations were not how I wanted.
If I use LMC6482 as in following way:
Here are plots for input to the non inverting input(blue), output of the op amp and the power dissipated:
As you see above output voltage is not pulled to zero also note that the pulses get distorted. And so much power is dissipated.
And if I use the following one:
Now the power dissipation is less but there is like 8mV offset again in the output when PWM is OFF. In INAMP it goes to zero.
I also tried with LM358 same issue.
Maybe better to draw a sketch of the topology what you mean if my circuit is wrong. Thanks.
is that your IRL3803 is already a logic level N channel mosfet (a very good one for this application by the way..), which means, you can drive it directly from the MCU_PWM pin with a properly selected resistor at the gate.
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That is necessary only if you implement the active low pass filter suggested by Klauss. If you stick with the Instrumentation OP amp, you are good...
Solution 1): you can use an active filter with high order (e.g. 3rd order suggested by crutshow) but with no gain. You can use a simple passive RC LPF.
Solution 2): doing it like Klauss suggested, current sensing must be on the soruce path.
How can I design an active 2nd order butterworth with gain for about 20Hz LPF?
Is there a practical tool for that when you plug in 20Hz cut off and gain it outputs the component values on a topology?
If I can have that I wouldn't need the -5V voltage converter and an INAMP.
How can I design an active 2nd order butterworth with gain for about 20Hz LPF?
Is there a practical tool for that when you plug in 20Hz cut off and gain it outputs the component values on a topology?