The ULN2004AI is a high-voltage, high-current Darlington transistor array. This device 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 500 mA. The Darlington pairs can 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.
The ULN2004AI has a 10.5-k. series base resistor for each Darlington pair for operation directly with TTL or 5-V CMOS devices.