ULN2003A

Overview

The ULN2003A is a high-voltage, high-current seven Darlington transistor array manufactured by STMicroelectronics. It contains seven independent NPN open-collector Darlington pairs with common emitters. Each channel supports a continuous collector current of 500 mA and withstands peak currents up to 600 mA. The device features an output voltage rating of 50 V and includes integrated suppression diodes for driving inductive loads. Inputs are pinned opposite outputs to simplify PCB layout. It interfaces directly with 5 V TTL and CMOS logic families. The component is available in a 16-pin PDIP package with dimensions of 20 mm length, 7.1 mm width, and 5.1 mm height.

Feature Summary

• Seven independent NPN Darlington pairs with common emitter configuration
• Integrated suppression diodes for handling inductive load back-EMF
• Direct interface compatibility with 5 V TTL and CMOS logic families
• Opposite pinning arrangement of inputs and outputs to facilitate board layout

Applications

• Relay drivers
• Stepper and brushed DC motor drivers
• LED display and filament lamp drivers
• Thermal printhead drivers
• High-power buffers and line drivers

Procurement Notes

Verify the manufacturer marking on the component body to confirm STMicroelectronics origin. Check the package type against the required form factor, as variants exist in SOIC packages. Ensure the specific orderable part number matches the exact suffix requirements for your manufacturing process. Confirm that the received components match the specified electrical characteristics before integration into the final assembly.

Selection Notes

Select this component when interfacing microcontrollers with loads requiring currents exceeding standard GPIO capabilities. The 500 mA per channel rating suits most small relays and solenoids. Verify that the load voltage does not exceed the 50 V collector-emitter rating. Consider paralleling outputs if the application demands current higher than the single-channel limit. Ensure the logic family voltage levels align with the 5 V TTL/CMOS input specifications.

Part Context

The ULN2003A belongs to the ULN2000 series of high-voltage Darlington arrays from STMicroelectronics. This series includes variants like ULN2001, ULN2002, and ULN2004, which differ primarily in internal base resistor values to optimize compatibility with different logic families such as PMOS or DTL. The ULN2003A specifically targets 5 V logic systems. All variants share the same seven-channel architecture and physical package options.

Replacement Considerations

Compatible substitutes include the SN75468 and SN75469 for 100 V versions. Other equivalents within the ULN2000 series may be used if logic level requirements differ. Verify pinout compatibility and thermal resistance characteristics when substituting with components from other manufacturers.