Understanding the 74ls279 Datasheet What It Is and How It's Used
The 74ls279 is a versatile quad bipolar latch IC. In simpler terms, it's a digital memory element capable of "remembering" a state (either a logic HIGH or a logic LOW). The "quad" part means it contains four independent latch circuits within a single package. Each latch has two inputs, a Set (S) input and a Reset (R) input, and a Data (D) input. The magic happens when you apply signals to these inputs. The primary function of the 74LS279 is to store binary information. Think of it like a light switch that can be turned ON (Set) or OFF (Reset) independently, and it will maintain that state until told otherwise. The Data input allows you to load a specific value into the latch when it's not being actively Set or Reset. The 74ls279 datasheet details how these inputs interact:- Setting the latch makes its output HIGH.
- Resetting the latch makes its output LOW.
- If both Set and Reset are activated simultaneously, the behavior is defined by the specific implementation, and the datasheet will clarify this.
- The Data input is often used to capture and hold a value when the latch is not being overridden by Set or Reset signals.
- Data storage in registers
- Creating debounced switches
- Building state machines
- Memory elements in counters and shift registers
| Set (S) | Reset (R) | Data (D) | Output (Q) |
|---|---|---|---|
| HIGH | LOW | X (don't care) | HIGH |
| LOW | HIGH | X (don't care) | LOW |
| LOW | LOW | HIGH | HIGH |
| LOW | LOW | LOW | LOW |