The ULN2003A and ULN2004A are monolithic highvoltage, high-current Darlington transistor arrays.
Each consists of seven NPN Darlington pairs that feature high-voltage outputs with common-cathode clamp diodes for switching inductive loads.
The collector-current rating of a single Darlington pair is 500mA.
The Darlington pairs may be paralleled for higher current capability.
Applications include relay drivers,
hammer drivers, lamp drivers, display drivers (LED and gas discharge), line drivers, and logic buffers.