Darlington NPN Transistors – ST TIP121, The 5A 80V TIP121 from ST is a complementary power Darlington transistor that is manufactured using planar technology with a ‘base island’ layout and monolithic Darlington configuration. The resulting transistor has exceptional high gain performance coupled with very low saturation voltage. Ideal for use in general purpose linear and switching applications. ST TIP121 65W 5A 80V TO220 NPN Darlington Transistor