The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC. 74LS257 is designed to multiplex signals from four-bit data sources to four-output data lines in the bus-organized systems. The 3-state outputs will not load the data lines when the output control pin (G) is at a high logic level.
74LS257 Features
- Tri-State Version of the 74LS157
- Schottky Diode Clamped for Improved AC Performance
- Provides Bus Interface from Multiple Sources
- Fast Switching Speeds
- Standard TTL Switching Voltages
74LS257 Specifications
| Supply Voltage | 4.75 – 5.25Vdc |
| Maximum Clock Frequency | 40Mhz |
| Power Dissipation | 2mW/gate @100kHz |
| Minimum Output Current | 8mA |
| Propagation Delay | 10nS |
| Fan Out (TTL Loads) | 20 |
74LS257 Pinout Diagram
74LS257 Pin Description
| Pin No | Pin Name | Description |
| 1 | S | Select Pin |
| 2 | I0a | Input Pin Of Multiplexer a |
| 3 | I1a | Input Pin Of Multiplexer a |
| 4 | Za | Output Of Multiplexer (a) |
| 5 | I0b | Input Pin Of Multiplexer b |
| 6 | I1b | Input Pin Of Multiplexer b |
| 7 | Zb | Output Of Multiplexer (b) |
| 8 | GND | Ground |
| 9 | Zd | Output Of Multiplexer (d) |
| 10 | I1d | Input Pin Of Multiplexer d |
| 11 | I0d | Input Pin Of Multiplexer d |
| 12 | Zc | Output Of Multiplexer (c) |
| 13 | I1c | Input Pin Of Multiplexer c |
| 14 | I0c | Input Pin Of Multiplexer c |
| 15 | E’0 | Enable Output (Active Low) |
| 16 | VCC | Positive Supply |
Applications
- Multiple data can be transmitted using a single line.
74LS257 Alternative Equivalent
74LS251, 74LS253
Download 74LS257 Quad 2-Input Multiplexer Tri-State Datasheet from the link given below.
