Open-drain hex inverter for wired-OR and level-shifting logic
The SN74HC05NSR is a 74HC-series hex inverter with open-drain outputs — each of the six inverters can sink up to 5.2 mA per channel, but the output high side is floating, not actively pulled up.
What the open-drain output means for your bus
The key spec that separates this from a standard 74HC04 inverter is the output stage: current-sink capability is 5.2 mA (low-level output), but there is no high-level output current listed — because the output transistor simply turns off and lets the external pull-up do the work. Propagation delay is 20 ns typical at 6V with a 50 pF load, which sets the practical data rate ceiling for the open-drain bus; at lower supply voltages the delay increases, so budget extra margin if running at 2V. Quiescent current is just 2 µA max — the part draws almost nothing when the outputs are static, which matters for always-on logic in battery-powered equipment where every microamp counts. Input logic thresholds are 0.5V to 1.8V for low and 1.5V to 4.2V for high, compatible with both 3.3V and 5V CMOS families without extra glue.
The SN74HC05NSR comes in a 14-SOIC package with 5.30 mm body width (the wider SOIC-14 variant, not the narrow 3.90 mm).