SN74HC257N

Logic - Signal Switches, Multiplexers, Decoders

SN74HC257N is an integrated circuit chip utilizing the high-speed CMOS logic, and is capable of performing a variety of tasks when it comes to the transfer of logic-level signals. It acts as a switch which then involves multiplexers, decoders, or both, and can be used for multiple applications. Generally, the SN74HC257N is designed as an 8-bit multiplexer with eight inputs containing two data selectors and a single inverted output. It can be used to transfer two 8-bit signals while selecting any two of four available sources.

The main application field of the SN74HC257N is to build a multi-channel data transmission system. The power requirement of this IC is very less, only 4.5V to 5.5V. Moreover, the propagation delay time of this IC is very low (3.4ns at 5V) which makes the system speed faster. The SN74HC257N can also be used to build timing systems for frequency divider, integer and fractional divider, phase detector, and other applications.

The electric diagram of SN74HC257N shows 2x4-channel data selector, 2x4-channel multiplexer, 4-channel decoder, 4-channel encoder, etc. When the two select inputs (Select A and B) are at logic low, the output will be connected to the first input (A0 and B0), and similarly when the two select inputs are logic high, the output is connected to the second input (A1 and B1). When both select inputs are at logical low, the inverter output will be always at logical high, and when both select inputs are at logical high, the inverter output will be at logic low.

The working principle of the SN74HC257N can be understood by the logic diagram. In essence, the SN74HC257N selects one of the two sets of inputs, A and B. This selection is made by the 4-bit select inputs (SEL A and SEL B) which are connected to both the A and B inputs. When both SEL inputs are high, the device will select the B inputs, and when both SEL inputs are low, the device will select the A inputs.

The SN74HC257N is an ideal choice for applications requiring faster data transfer and data conversion. The device’s small size makes it suitable for use in high-density applications, and the low power consumption makes it highly suitable for battery-powered devices. The SN74HC257N can also be used as a bus-transceiver, connect two buses to a single bus, and serve as an address decoder.