five-volt-logicheader / SDA
Powered from 5 V, this board's SDA and SCL idle at 5 V because whatever pulls the bus up pulls it up to VCC. That is above the absolute maximum of every 3.3 V microcontroller pin.
- Domain
- MCU
- Ports
- 1
- Conductors
- 4
- Source
- Marketplace listing
Ports and conductors
Every conductor Zikro reasons about on this device, with the voltage it sits at in normal use and the voltage past which the pin can be damaged. These figures are compared against the other side of a connection, so a wrong row here becomes a wrong verdict.
VCC GND SDA SCL header
2.54 mm header, 4-pin male| Conductor | Contact | Signal class | Direction | Nominal | Abs max | Impedance | DC bias |
|---|---|---|---|---|---|---|---|
| VCC | 1 | Power rail | Input | 5 V | 6 V / 20 mA | unknown | None |
| GND | 2 | Power rail | Bidirectional | 0 V | unknown | out 0 Ω | None |
| SDA | 3 | I2C bus | Bidirectional | 5 V | 6 V / 20 mA | unknown | None |
| SCL | 4 | I2C bus | Bidirectional | 5 V | 6 V / 20 mA | unknown | None |
Quirks
The things no numeric field carries, and the things that actually break builds.
no-onboard-pullupheader / SDA
Many cheap breakouts have no bus pull-up resistors fitted at all, and the ones that do rarely say so. Assume none until you have looked at the board.
voltage-tolerantheader / VCC
Boards in this class usually run on either 3.3 V or 5 V. Powering it from 3.3 V instead is very often the whole fix, because then the bus idles at 3.3 V and needs no level shifting.
unverified
This describes the common shape of a four-pin I2C breakout rather than one specific part. Check your own module's silkscreen: the pin order is not standardised and VCC and GND are sometimes swapped.
Check this against what you are wiring it to
Put both devices in a project, connect the actual conductors, and read the verdict before you solder anything.
Use in a projectRelated devices
Last reviewed 30 Aug 2026, sourced from marketplace listing.