Catalog > Semiconductors > Integrated Circuits 7439 Buffer Quad 2-Input NAND Buffer with Open Collector Outputs (Input and Output Terminals Flipped) Part No: 7439 20.64 ZAR inc for 1 Each (Quoting) Add to Cart Specifications, Prices & Availability may change without notice. Images are for illustration purposes only. E&OE Features Function: Quad 2-input NAND buffer. Output Type: Open collector, which requires pull-up resistors for proper operation. Applications: Open collector outputs allow for connecting to other similar outputs to implement active-low wired-OR or active-high wired-AND functions. Voltage Levels: Often used to generate higher VOHcap V sub cap O cap H end-sub𝑉𝑂𝐻 (Voltage Output High) levels. Logic Family: Part of the 7400 series TTL logic family.