STP20NM50-VB STP20NM60 STP20NM60 MOSFET或IGBT开关IC STP20NM60 P20NM60 STP20NM60A STP20NM60A-VB STP20NM60FD STP20NM60FD MOSFET或IGBT STP20NM60FD P20NM60FD STP20NM60FD-VB