NE555 Pinout
NE555 Timer · Classic timer/oscillator IC; works as monostable, astable, or PWM.
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | GND | GND | Ground |
| 2 | TRIG | Input | Trigger (fires below 1/3 VCC) |
| 3 | OUT | Output | Output |
| 4 | RESET | Control | Reset (active-low; tie to VCC when unused) |
| 5 | CTRL | Control | Control voltage (tie to ground via 10nF when unused) |
| 6 | THRES | Input | Threshold (flips above 2/3 VCC) |
| 7 | DISCH | Output | Discharge (connects to the timing capacitor) |
| 8 | VCC | Power | Supply + (4.5–15V) |
How to read the NE555 pinout
- 01
Find pin 1
One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.
- 02
Count counter-clockwise
Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.
- 03
Check the table below
Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.
Frequently asked questions
How do I connect the RESET pin if unused?
Tie it to VCC (high). Leaving it floating can cause spurious resets.
Do I need to handle CTRL (pin 5) if unused?
Tie it to ground via a 10nF capacitor to filter noise; it works without one but has poorer noise immunity.
How much current can the 555 output?
Typically sinks/sources about 200mA, enough to drive a small buzzer/LED directly; use a transistor for larger loads.
Pinout data comes from TI NE555 datasheet (standard DIP-8 numbering). Refer to the actual device datasheet as authoritative for the pinout.