The ULN2003A is a monolithic 7-channel NPN Darlington transistor array with open-collector outputs rated to 50V and 500mA per channel. An integrated 2.7kΩ series base resistor on each channel allows direct interfacing with 5V TTL or 3.3V CMOS logic — no external resistors required. Internal flyback diodes on every output enable direct switching of inductive loads including relays, solenoids, and stepper motors. Channels may be paralleled for higher current capacity, up to 2.5A total device current.

This DIP package is often used for driving small stepper motors or other higher-load and often inductive loads for up to 50V. The channels are only 500mA rated, but that’s often quite adequate for driving steppers, small DC motors or relays.

Key Specifications

• 500mA Max collector current per channel
• 50V Max output voltage (Vce)
• 7 Independent channels
• 2.5A Max total emitter current
• 2.7kΩ Series base resistor (per ch.)
• 1.0µs Max propagation delay (tPHL)
• −40°C Min operating temperature
• 105°C Max operating temp (AI grade)

Applications

• Relay drivers (12V / 24V / 48V coils)
• Stepper motor drivers (unipolar)
• DC brushed motor control
• LED array / display drivers
• Solenoid and valve control
• Lamp drivers
• Logic-level buffer and line driver