WHY USE SEMI F47?

The voltage sags required by SEMI F47 typically occur about once per month in semiconductor fabs (fabrication facilities) around the world. So industrial equipment that cannot tolerate these sags typically fails, without explanation, about once per month.

A typical SEMI F47 voltage sag (top) and how it affects a power supply (bottom). This problem was fixed by increasing the size of a capacitor, at a cost of a few dollars.