74LS283 4-bit binary full adder
The 74LS283 is a 4-bit binary full adder with fast carry. It adds the two 4-bit numbers A4–A1 and B4–B1 together with the carry-in C0, and gives the 4-bit sum S4–S1 and the carry-out C4. In arithmetic terms, C4 S4 S3 S2 S1 = A + B + C0.
74LS283 pinout
Top view of the 16-pin DIP package. Pin 1 is at the bottom left, beside the notch, and the numbers run anticlockwise. Power is on pin 16 (VCC, +5 V) and pin 8 (GND).
| Pin | Name | Type | What it is |
|---|---|---|---|
| 1 | S2 | Output | Totem-pole output |
| 2 | B2 | Input | Input |
| 3 | A2 | Input | Input |
| 4 | S1 | Output | Totem-pole output |
| 5 | A1 | Input | Input |
| 6 | B1 | Input | Input |
| 7 | C0 | Input | Input |
| 8 | GND | Ground | 0 V |
| 9 | C4 | Output | Totem-pole output |
| 10 | S4 | Output | Totem-pole output |
| 11 | B4 | Input | Input |
| 12 | A4 | Input | Input |
| 13 | S3 | Output | Totem-pole output |
| 14 | A3 | Input | Input |
| 15 | B3 | Input | Input |
| 16 | VCC | Power | +5 V supply |
74LS283 function table
| A | B | C0 | C4 | S (S4…S1) | In decimal |
|---|---|---|---|---|---|
| 0011 | 0001 | 0 | 0 | 0100 | 3 + 1 = 4 |
| 0101 | 0110 | 0 | 0 | 1011 | 5 + 6 = 11 |
| 0111 | 0111 | 1 | 0 | 1111 | 7 + 7 + 1 = 15 |
| 1001 | 1000 | 0 | 1 | 0001 | 9 + 8 = 17 |
| 1111 | 1111 | 1 | 1 | 1111 | 15 + 15 + 1 = 31 |
What the 74LS283 is used for
- Adding two 4-bit numbers
- 8-bit and wider adders, by connecting C4 of one chip to C0 of the next
- Subtraction, by inverting B with XOR gates and setting C0 to 1
- BCD adders and code converters
Electrical summary
| Package | 16-pin DIP |
| Supply voltage | 5 V (4.75 V to 5.25 V) |
| Supply current, typical | 19 mA |
| Output type | Totem-pole — drives both high and low |
| Output current, low | sinks up to 8 mA |
| Output current, high | sources up to 0.4 mA |
| Input current, low | 0.4 mA out of each input held low |
| Fan-out | one output can drive about 20 LS inputs |
Typical figures for quick reference when planning a board. Check the manufacturer's datasheet for limits and timing before committing a design. The 74HC283 and 74HCT283 use the same pin numbers, with different electrical values.
Try the 74LS283 on a breadboard
The Breadboard Simulator has the 74LS283 in its parts library: seat it on a virtual breadboard, wire it, power the board and probe the pins before you build the real thing.