The CY74FCT157CTD is a 4 x 2:1 multiplexer from the 74FCT logic family, packaged in a 16-pin SOIC for surface-mount assembly. It selects one of two 4-bit data sources onto a common output bus, controlled by a single select line. The independent circuit count of 1 means all four mux sections share the same select and enable — you get one quad mux, not four standalone switches. Output drive is 32 mA high, 64 mA low.
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