5V-only octal bus transceiver for industrial backplanes
The CY74FCT245ATQCT from Cypress (now Infineon) is an 8-bit non-inverting bus transceiver in the 74FCT logic family, designed for bidirectional data flow between two 5V buses with 3-state outputs on both ports. It operates from a 4.75V to 5.25V supply — strictly a 5V part, not 3.3V-tolerant on the I/O — and delivers 32mA source / 64mA sink per output, enough to drive heavily loaded backplanes or long PCB traces without external buffers.
Supply voltage and 3.3V compatibility
The supply range is 4.75V to 5.25V, and the logic inputs are not 3.3V-compatible. If your design uses a 3.3V microcontroller or FPGA on one side of the bus, you need a level-shifting transceiver like the SN74LVTH16245ADGVR (2.7V supply, 3.3V I/O tolerant). The CY74FCT245ATQCT is a 5V-only part — applying 3.3V to the VCC rail will not meet the minimum operating voltage, and driving the inputs with 3.3V logic may not cross the VIH threshold reliably.
With 32mA source and 64mA sink per channel, this part can drive a 50-ohm terminated backplane or a bank of parallel inputs without needing a separate line driver. The asymmetric drive (more sink than source) matches the typical current draw of TTL-compatible loads. For lighter loads — say, a single 3.3V-tolerant peripheral through a level shifter — the SN74ABT2245DW offers similar drive at 4.5V minimum supply but in a wider SOIC-20 package.
ROHS3 compliant.