Pinout
DC barrel jack (5.5×2.1mm) pinout
Pins
- Center pin: usually +V (check the device — polarity is not standardized)
- Outer sleeve: usually GND/−V
Specifications
| Contacts | 2 (centre pin, sleeve) + often a switch contact |
|---|---|
| Plug outer diameter | 5.5 mm |
| Centre pin diameter | 2.1 mm |
| Polarity | Usually centre positive (not standardized) |
| Typical jack rating | 2–5 A, 12–24 V DC (part dependent) |
| Other common sizes | 5.5 × 2.5, 3.5 × 1.35, 4.0 × 1.7 mm |
| Typical use | Arduino Uno (7–12 V), 12 V LED strips, routers |
Notes
- 5.5×2.1 mm is the plug's outer diameter by the diameter of the hole its centre contact slides over. Other common sizes are 5.5×2.5, 3.5×1.35 and 4.0×1.7 mm.
- A 2.5 mm plug will not go onto a 2.1 mm centre pin; the other way round, a 2.1 mm plug on a 2.5 mm pin fits loosely and drops the connection with a nudge.
- The polarity symbol printed by a jack or on a supply - a dot inside a C-shaped arc, + on the dot - means centre positive. Most hobby supplies are, but a reversed supply into a board with no protection diode can destroy it.
