I have designed this circuit and math calculation works but looking back now I feel the cap is too small may be I am making any mistake here? Can some one explain how to chose the capacitor for AC coupling the relay driver. Please do not engage in to side discussion, why I would want to drive relay with AC signal.
Note: RLY_RUN is PWM signal, which is changed to 5V level by U63 and 100R & 47 nF acts as AC coupling to drive the U23 MOSFET. the relay used here is 24 V DC relay .
I couldn't find any design or application note on this anywhere on the Internet so far.