ULN2805A

Overview

The ULN2805A is an eight-channel high-voltage, high-current Darlington transistor array manufactured by STMicroelectronics. It features eight NPN Darlington pairs with common emitters and integral suppression diodes for inductive load switching. Each channel supports a continuous collector current of 500 mA and withstands output voltages up to 50 V. The device is specifically designed to sink a minimum of 350 mA for standard and Schottky TTL logic families where higher output current capability is required. It is supplied in an 18-lead plastic DIP package.

Feature Summary

• Eight independent Darlington transistor channels with common emitter configuration
• Integrated suppression diodes for driving inductive loads
• Optimized input characteristics for standard and Schottky TTL logic families
• High current sinking capability with outputs pinned opposite inputs

Applications

• Standard and Schottky TTL driver applications requiring high output current
• Relay drivers
• Hammer drivers
• Lamp and display (LED) drivers

Procurement Notes

Verify the specific manufacturer part number against official STMicroelectronics documentation to ensure authenticity. Confirm that the component matches the 18-lead DIP package specification. Check datasheet revisions for any updates to electrical characteristics or thermal ratings before finalizing procurement specifications.

Selection Notes

Select the ULN2805A when interfacing with standard or Schottky TTL logic circuits that require a minimum sink current of 350 mA per channel. This variant differs from other ULN280x series members primarily through its input resistor network tailored for these specific logic families. Ensure the application does not exceed the 500 mA continuous collector current rating per output.

Part Context

The ULN2805A belongs to the ULN2801A through ULN2805A family of eight Darlington arrays produced by STMicroelectronics. While sharing the same physical package and core Darlington structure, this specific model is distinguished by its input circuitry designed for TTL compatibility. Other variants in the series target PMOS, CMOS, or general-purpose applications with different input resistance values.

Replacement Considerations

Direct functional substitutes within the same STMicroelectronics lineup include the ULN2801A, ULN2802A, ULN2803A, and ULN2804A. Note that these alternatives feature different input resistor networks optimized for PMOS, 5V CMOS/TTL, or 6-15V CMOS logic rather than the specific TTL requirements of the ULN2805A.