ULN2074B

Overview

The ULN2074B is a quad NPN Darlington transistor array manufactured by STMicroelectronics, housed in a 16-pin PDIP package for through-hole mounting. Each of the four internal switches delivers a maximum continuous collector current of 1.5 A with a minimum breakdown voltage (Vceo) of 50 V and a sustaining voltage of at least 35 V at 100 mA. The device features isolated Darlington pinouts, distinguishing it from common-emitter variants, making it suitable for emitter follower configurations. It operates within a temperature range of -20°C to +85°C, with a maximum power dissipation of 4.3 W and a typical collector-emitter saturation voltage of 1.4 V.

Feature Summary

• Isolated Darlington pinout configuration designed specifically for emitter follower applications
• High output current capability of up to 1.5 A per switch
• Integral suppression diodes included for handling inductive loads
• Input compatibility with popular 5 V logic families

Applications

• Interface circuits connecting logic signals to high current or high voltage loads
• Emitter follower configurations requiring isolated switching outputs
• Driving inductive loads such as relays, solenoids, or motors where suppression diodes are required

Procurement Notes

Verify the specific ordering suffix against the manufacturer's official datasheet to ensure correct packaging and tape-and-reel options if applicable. Confirm that the 16-pin PDIP package meets the mechanical constraints of the target PCB layout. Ensure the operating environment stays within the specified -20°C to +85°C range to maintain rated performance parameters.

Selection Notes

Select the ULN2074B over common-emitter variants like the ULN2068B when an emitter follower topology is required rather than a common ground reference. Verify that the load current does not exceed 1.5 A per channel and that the supply voltage remains below the 50 V breakdown limit. Consider thermal management requirements given the 4.3 W total power dissipation rating in the PDIP package.

Part Context

The ULN2074B belongs to the ULN20xxB series of quad Darlington arrays from STMicroelectronics. Unlike the ULN2064B, ULN2066B, and ULN2068B which share common emitters, this variant provides isolated outputs. This distinction allows designers to implement different circuit topologies, particularly those needing separate emitter references or active pull-up arrangements via emitter followers.

Replacement Considerations

The ULN2068B serves as a functional alternative but utilizes a common emitter configuration rather than isolated pinouts. Substitution requires verifying that the circuit design can accommodate the common emitter topology instead of the isolated structure intended for the ULN2074B.