The NE556 is a dual 555 timer in a 14-pin DIP package, providing two independent timer circuits sharing a common VCC and GND. Each timer is functionally identical to the NE555.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | DIS1 | Timer 1 discharge | I/O |
| 2 | CTRL1 | Timer 1 control voltage | ADC |
| 3 | THR1 | Timer 1 threshold | I/O |
| 4 | OUT1 | Timer 1 output | I/O |
| 5 | RESET1 | Timer 1 reset, active low | I/O |
| 6 | TRIG1 | Timer 1 trigger | I/O |
| 7 | GND | Ground | GND |
| 8 | TRIG2 | Timer 2 trigger | I/O |
| 9 | RESET2 | Timer 2 reset, active low | I/O |
| 10 | OUT2 | Timer 2 output | I/O |
| 11 | THR2 | Timer 2 threshold | I/O |
| 12 | CTRL2 | Timer 2 control voltage | ADC |
| 13 | DIS2 | Timer 2 discharge | I/O |
| 14 | VCC | Supply 4.5Vā16V | PWR |