The 74LS279 IC consists of four individual and independent Set-Reset Latches with active-low inputs. Two of the four comprising latches have an additional S input ANDed with the primary S input. A LOW on any S input, while the R input is HIGH, will be stored in the latch and appear on the corresponding Q output as a HIGH. The output of the IC always comes in a Push-Pull configuration which makes it easy to work with other devices and microcontrollers. The IC offers a wide array of features such as variable operating voltages, ESD protection & thermal overload protection.
What is an S-R Latch?
An SR latch or an SR Flip-Flop is a combinational logic circuit, that has two inputs S and R, and two outputs Q and Q’. The state of this latch is determined by the condition of output Q. If output Q is 1 (High) the latch is said to be SET and if Q is 0 (Low) the latch is said to be RESET. An SR Latch or Flip flop can be designed either by two cross-coupled NAND gates or two-cross coupled NOR gates.
74LS279 Pinout
74LS279 Pin Configuration
| Pin No | Pin Name | Description |
|---|---|---|
| 1 | R’ | Active Low Reset Pin |
| 2 | S1′ | Active low Set Pin 1 |
| 3 | S2′ | Active low Set Pin 2 |
| 4 | Q | Latch Output pin |
| 5 | R’ | Active Low Reset Pin |
| 6 | S1′ | Active low Set Pin 1 |
| 7 | Q | Latch Output pin |
| 8 | GND | Ground Pin |
| 9 | Q | Latch Output pin |
| 10 | R’ | Active Low Reset Pin |
| 11 | S2′ | Active low Set Pin 2 |
| 12 | S1′ | Active low Set Pin 1 |
| 13 | Q | Latch Output pin |
| 14 | R’ | Active Low Reset Pin |
| 15 | S1′ | Active low Set Pin 1 |
| 16 | Vcc | Chip Supply Voltage |
74LS279 Features & Specifications
- Function: RS latch
- Channels (#): 4
- Technology Family: LS
- Inputs Voltage Level Triggered
- Fast Propagation Times
- Operating Temperature up to 70°C
- Standard TTL Switching Voltages
- VCC (Min): 4.75V
- VCC (Max): 5.25V
- Input type: Bipolar
- Output type: Push-Pull
- Data rate (Max): 70Mbps
- IOL (Max): 8mA
- IOH (Max): -0.4mA
- Propagation speed: (tpd 5-10ns)
Applications
- Generally used as a storage element which are widely used in computing as well as data storage applications.
- Also used in synchronous two-phase systems for reducing the transit count.
You can download this datasheet for 74LS279 Quad (Set-Reset) S-R Flip Flop Latch IC from the link given below:
See Also: 74LS135 Quad 2-Input XOR Logic Gate IC – Datasheet | 74LS122 Retriggerable Monostable Multivibrator IC – Datasheet | 74LS91 8-Bit Shift Storage Register IC – Datasheet
