74LS83 4-bit binary full adder (original pinout)
The 74LS83 adds two 4-bit numbers and a carry-in, the same job as the 74LS283, with the older pinout many lab manuals still draw as the 7483: VCC on pin 5 and GND on pin 12 rather than on the corners. C4 S4 S3 S2 S1 = A + B + C0.
74LS83 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 5 (VCC, +5 V) and pin 12 (GND).
| Pin | Name | Type | What it is |
|---|---|---|---|
| 1 | A4 | Input | Input |
| 2 | S3 | Output | Totem-pole output |
| 3 | A3 | Input | Input |
| 4 | B3 | Input | Input |
| 5 | VCC | Power | +5 V supply |
| 6 | S2 | Output | Totem-pole output |
| 7 | B2 | Input | Input |
| 8 | A2 | Input | Input |
| 9 | S1 | Output | Totem-pole output |
| 10 | A1 | Input | Input |
| 11 | B1 | Input | Input |
| 12 | GND | Ground | 0 V |
| 13 | C0 | Input | Input |
| 14 | C4 | Output | Totem-pole output |
| 15 | S4 | Output | Totem-pole output |
| 16 | B4 | Input | Input |
74LS83 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 |
| 1001 | 1000 | 0 | 1 | 0001 | 9 + 8 = 17 |
What the 74LS83 is used for
- Adding two 4-bit numbers
- Wider adders, chaining C4 into the next C0
- Subtraction, with B inverted and C0 set to 1
- BCD adders, with a correction of 6 when the sum passes 9
The 74LS283's circuit with the older pinout many lab manuals draw as the 7483: the supply is on pins 5 (VCC) and 12 (GND), not the corners.
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 74HC83 and 74HCT83 use the same pin numbers, with different electrical values.
Try the 74LS83 on a breadboard
The Breadboard Simulator has the 74LS83 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.