Single-gate buffer for mixed-voltage buses
The Texas Instruments 74AHC1G126DCKTE4 is a single-bit non-inverting buffer with a 3-state output, part of the 74AHC logic family. The output delivers 8mA source and sink, enough to drive a handful of CMOS inputs or a short PCB trace without an extra line driver.
2V to 5.5V supply — covers the common rails
The supply range spans 2V to 5.5V, so the same part works on a 3.3V MCU bus, a 5V legacy peripheral, or a 2.5V FPGA I/O bank. No level translator needed when the buffer sits between a 3.3V controller and a 5V sensor — the input threshold tracks VCC. At 3.3V the part is fully specified; at 5V the output drive stays at 8mA, which keeps the thermal dissipation predictable.
8mA output — fan-out and drive budget
With 8mA output high and 8mA output low, the buffer can drive up to ten 74AHC inputs (each loads about 0.8mA at 5V) or a single optocoupler LED with a series resistor. For heavier loads — a relay coil or a long cable — you will want a discrete transistor or a bus driver with higher current rating. The 3-state output lets you share a data line with other drivers; the high-impedance state floats the output cleanly.
The 125°C ceiling also covers the hot side of a power supply or a motor-drive control board near the heatsink.
SC-70-5 package — tight footprint
Housed in a 5-lead SC-70-5 (also called SOT-353), the part occupies about 2.0 mm × 2.1 mm of board area. That is small enough to slip into a cramped corner of a multi-layer PCB where a larger SOIC-8 would not fit. The leads are on a 0.65 mm pitch, so standard fine-pitch soldering works; no special stencil required.