A.The input of the switching power supply is assumed to be a sine wave, and a square wave is not guaranteed.
A sine wave is recommended for the input.
The main concerns for square wave input are as follows:
1) Products with internal harmonic current suppression (power factor correction) circuits adjust input current in response to sudden changes in input voltage, which may result in excessive current flow.
2) Sudden changes in input voltage may cause a buzzing sound from the input filter of the power supply.