MCP9808 — i2c address & wiring
±0.25 °C typical accuracy temperature — the precision upgrade over hobby temp sensors.
Key facts
MCP9808 at a glance
| i2c address | 0x180x190x1A0x1B0x1C0x1D0x1E0x1F address-selectable via pins/jumpers |
|---|---|
| Logic voltage | 2.7–5.5 V |
| Type | sensor |
| Part | Microchip MCP9808 |
| Ships with | STEMMA QT |
| Datasheet | Microchip MCP9808 — manufacturer documentation ↗ |
The chip
What the Microchip MCP9808 actually is
High-accuracy digital temperature sensor featuring programmable resolution, configurable temperature alerts and low-power operation. Provides measurement resolution down to 0.0625 °C with typical accuracy of ±0.25 °C near room temperature.
Wiring
How to connect the MCP9808
The MCP9808 talks i2c at address 0x18 (up to 8 selectable addresses, handy when you need more than one on the same bus). It runs at 2.7–5.5 V, so match your host's logic level — if your host is 5 V and a board on the bus is 3.3 V-only, add a level shifter. Use the compatibility checker to confirm the exact cable for your setup.
Because the address is selectable, you can run several MCP9808 boards on one bus by setting each to a different address — no extra wiring beyond the shared SDA/SCL.
Wiring is the usual four: power, ground, SDA and SCL, plus pull-up resistors — almost always already fitted on the breakout. Nothing showing up? Run an i2c scan first; if the bus is silent, the 7-step checklist finds it faster than guessing.
Ecosystems
Plug-together options for the MCP9808
MCP9808 breakouts ship with STEMMA QT — keyed 4-pin cables carrying power, ground, SDA and SCL, so there's nothing to solder and nothing to wire backwards. Chain it to the next board and keep going.
Running a mixed bench? Those ecosystems interoperate more than their marketing suggests — see every connector pairing for the cable or adapter you need, or the standards overview for how they compare.
Go deeper
Guides covering the MCP9808
Alternatives
Other environmental boards
Watch the bus
Boards that clash with the MCP9808
These want addresses the MCP9808 also answers (0x18, 0x19, 0x1D, 0x1E, 0x1F), so they can't share a bus with it untouched. If one is address-selectable, strap it elsewhere; if not, the conflict guide covers the multiplexer and second-bus routes, and the collision roundup explains why a scan won't warn you.
Get one
Questions
MCP9808 i2c FAQ
What is the MCP9808's i2c address?
The MCP9808 uses 0x18 or 0x19 or 0x1A or 0x1B or 0x1C or 0x1D or 0x1E or 0x1F, selected with an address pin or solder jumper on the board. If a scan turns up something unexpected, our i2c address list names the usual suspect for every address.
What voltage does the MCP9808 run at?
2.7–5.5 V logic. That range covers both 3.3 V and 5 V hosts, so it drops onto a Pi, ESP32 or Arduino without a level shifter.
Can I use two MCP9808s on one i2c bus?
Yes — set each one to a different address (0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F) using its address pin or jumper, then wire both to the same SDA/SCL. That gives you up to 8 on a single bus before you need a multiplexer.
Does the MCP9808 work with STEMMA QT?
Yes — MCP9808 breakouts ship with STEMMA QT, so it plugs straight in with no soldering. Mixing ecosystems? The compatibility checker gives you the exact cable or adapter.