DESCRIPTION
These IC’s are composed of an independent 2channel multiplexer with common SELECT and ENABLE INPUT. The M54/74HCT258 is an inverting multiplexer while the M54/74HCT257 is a non-inverting multiplexer. When the ENABLE INPUT is held ”High”, outputs of both IC’s become high-impedance state. If SELECT INPUT is held ”Low”, ”A” data is selected, when SELECT INPUT is high ”H”, ”B” data is chosen. All inputs are equipped with protection circuits against static discharge and transient excess voltage. This integrated circuit has input and output characteristics that are fully compatible with 54/74 LSTTL logic families. M54/74HCT devices are designed to directly interface HSC2MOS systems with TTL and NMOS components. They are also plug in replace- PIN CONNECTIONS (top view) HCT257 HCT258 February 1993 1/12 M54/M74HCT257/258 INPUT AND OUTPUT EQUIVALENT CIRCUIT CHIP CARRIER HCT257 HCT258 NC = No Internal Connection PIN DESCRIPTION
(HCT257) PIN No 1 2, 5, 14, 11 3, 6, 13, 10 4, 7, 12, 9 1...
STMicroelectronics
