ULQ2803A

Overview

The ULQ2803A is an octal Darlington transistor array manufactured by STMicroelectronics, designed for high-voltage and high-current switching applications. It integrates eight NPN Darlington pairs within a single package, featuring common emitters and integral suppression diodes to handle inductive load flyback currents. The device supports a continuous output current of 500 mA per channel with a peak rating of 600 mA, while withstanding up to 50 V in the off state. It includes a 2.7 kΩ input resistor optimized for direct interfacing with 5 V TTL and CMOS logic families. The component is housed in an 18-lead plastic DIP package with a copper lead frame.

Feature Summary

• Integrates eight Darlington transistors with common emitters and built-in suppression diodes for inductive load protection
• Features a 2.7 kΩ input resistor specifically configured for compatibility with 5 V TTL and CMOS logic levels
• Provides convenient input-opposite-output pinout arrangement to simplify printed circuit board layout

Applications

• Direct interface between microcontrollers or logic gates and high-power relays
• Driving stepper motors and solenoids requiring inductive load suppression
• General-purpose high-current switching in industrial control systems

Procurement Notes

Verify the specific manufacturer source when sourcing components, as multiple vendors produce this standard part number. Confirm that the received units match the STMicroelectronics specification sheet regarding electrical characteristics and physical dimensions. Ensure the package type corresponds to the required 18-lead DIP form factor for your design constraints.

Selection Notes

Select the ULQ2803A when the application requires driving loads directly from 5 V logic without external base resistors. This variant is distinct from other ULQ series members due to its specific 2.7 kΩ input resistance tailored for 5 V operation. Consider paralleling outputs if the total load current exceeds the 500 mA continuous limit per channel.

Part Context

This component belongs to the ULQ2801A through ULQ2804A family of high-voltage Darlington arrays. While electrically similar, each member differs primarily in input resistance values to suit different logic voltage standards. The ULQ2803A specifically targets 5 V systems, whereas variants like the ULQ2802A and ULQ2804A are designed for higher voltage PMOS or CMOS inputs.

Replacement Considerations

The ULN2803A serves as a functional equivalent with identical pinout and electrical specifications. Other compatible substitutes include ECG2018, NTE2018, SK9079, TCG2018, and TM2018. Verify that replacement parts maintain the same 2.7 kΩ input resistance to ensure proper logic interfacing.