The ULN2003 is a monolithic high voltage and high current Darlington transistor arrays. It consists of seven NPN darlington pairs that features high-voltage outputs with common-cathode clamp diode for switching inductive loads. The collector-current rating of a single darlington pair is 500mA. The darlington pairs may be parrlleled for higher current capability. Applications include relay drivers,hammer drivers, lampdrivers,display drivers(LED gas discharge),line drivers, and logic buffers.The ULN2003 has a 2.7kW series base resistor for each darlington pair for operation directly with TTL or 5V CMOS devices.