Open-drain NAND for wired-OR and level translation
The SN74HC03DR is a quad 2-input NAND gate from TI's 74HC family, distinguished by open-drain outputs. This means each output can sink current but cannot source it — the pull-up resistor is external. That topology is what makes wired-OR connections possible: multiple gate outputs tie to a common pull-up, so any gate going low pulls the bus low. Each of the four gates accepts two inputs and follows the NAND truth table: the output is low only when both inputs are high. The high-level output current is listed as "-" because the open-drain structure does not source current; the pull-up resistor handles that.
Supply range and timing for mixed-voltage boards
The supply voltage spans 2 V to 6 V, covering the full 74HC operating envelope. This makes the SN74HC03DR a natural fit for battery-operated 3.3 V logic or legacy 5 V TTL-replacement designs — the same part works across both rails without a separate regulator. Propagation delay is 23 ns maximum at 6 V with a 50 pF load. That is a middle-of-the-road figure for the 74HC family — fast enough for most control and status logic below 10 MHz, but not intended for high-speed data paths. The input logic thresholds scale with VCC: low-level is 0.5 V to 1.8 V, high-level is 1.5 V to 4.2 V, so the gate interprets a 3.3 V CMOS signal correctly at any supply in the range.
14-SOIC package and board integration
The SN74HC03DR comes in a 14-SOIC package with a body width of 3.90 mm (the narrow SOIC-14 footprint). It is surface-mount, intended for reflow soldering. The supplier device package is also listed as 14-SOIC, meaning the marking and the land pattern are consistent across TI's own documentation. The part is available in Tape & Reel (TR) or Cut Tape (CT) options — the reel format suits automated pick-and-place assembly, while cut tape works for prototype runs and small-batch builds.