ULN2001 is a dual transistor array produced by Motorola. It consists of 7 PNP transistors and 3 NPN transistors, which are used to drive common anode LEDs, COMS switches and transistors. ULN2001A is a stronger version of ULN2001, with a higher integration and a higher drive current. ULN2002 is the NPN version of ULN2001, with the same functions and characteristics.