Bus switch for 5 V logic isolation
The Texas Instruments SN74CBT3244PWR is a 74CBT-series bus switch that provides two independent 4-bit (4 x 1:1) switching circuits in a single 20-TSSOP package. It operates from a 4.5 V to 5.5 V single supply, making it suitable for isolating or multiplexing 5 V CMOS/TTL logic signals on a board. The industrial temperature range (-40°C to 85°C) covers factory automation, telecom infrastructure, and outdoor equipment where the bus needs to be disconnected without adding propagation delay.
Two 4-bit channels — what it means for the bus
With two independent circuits, each handling a 4-bit-wide data path, this switch can isolate two separate 4-bit buses or combine them for an 8-bit application with external gating. The 1:1 configuration means each switch passes one signal per channel without voltage translation. Because bus switches have near-zero propagation delay (typically under 250 ps), they are used for hot-swap isolation, bus sharing, or analog signal switching where a standard logic gate would add unacceptable delay.
Supply rail and temperature — fit check
The 4.5 V to 5.5 V supply range is a standard 5 V ±10% rail, common in legacy industrial and telecom backplanes. The device is not rated for 3.3 V operation — if your design runs a 3.3 V bus, look at the 74CBT family's 3.3 V variants. It fits indoor and outdoor enclosures without active cooling, but not under-hood or engine-bay environments.
Package and footprint
Housed in a 20-TSSOP (4.40 mm width) surface-mount package, the SN74CBT3244PWR uses a standard 0.65 mm pitch footprint. The small body saves board area compared to a 20-SOIC, but the fine pitch means careful stencil design for soldering.