Active 74ALS octal buffer — through-hole fit for legacy backplanes
The SN74ALS541N is a non-inverting octal buffer with 3-state outputs, part of TI's 74ALS family, in a 20-pin DIP package (0.300" width, 7.62 mm pitch). Output drive is specified at 15 mA source and 24 mA sink per channel, which is sufficient for driving TTL-level loads on a parallel bus or fanning out to multiple CMOS inputs without external buffers.
Sourcing and lifecycle — active production, no obsolescence risk
For BOM lines that require a through-hole octal buffer with 3-state outputs, this device is a direct fit. No pin-compatible second-source is formally cross-referenced in the TI documentation, but the 74ALS family is widely second-sourced by multiple vendors — confirm the specific order code against your BOM position before committing.
What the output drive rating means for your bus
The 15 mA source / 24 mA sink capability determines how many standard TTL loads the buffer can drive without signal degradation. A single TTL input typically draws 1.6 mA low and 40 µA high, so one SN74ALS541N output can fan out to roughly 15 TTL loads on the low side — enough for a moderate-width address or data bus on a legacy backplane. The 3-state output allows the buffer to be placed in high-impedance mode, enabling multiple devices to share a common bus without contention. This is essential for multiplexed data buses in microprocessor systems or shared peripheral interfaces.