Pinout
MAX6675 K-type thermocouple amplifier (SPI module) pinout
Pins
- GND
- VCC (3.0–5.5V — the chip does its own cold-junction compensation from its own die temperature, so keep the module at ambient and well away from the heat source)
- SCK (SPI clock input, 4.3MHz max — the MAX6675 is read-only, there is no MOSI/DI pin and no register to write)
- CS (chip select, active low — pulling it low starts a 16-bit read; a conversion takes up to 0.22s, so poll no faster than about 4–5 times a second)
- SO (serial data out, wire it to the MCU MISO — it swings to VCC, so a 5V-powered module drives 5V into a 3.3V MCU. Range is 0 to +1024°C in 0.25°C steps: it cannot read below 0°C)
- T+ (screw terminal, K-type thermocouple positive — the yellow chromel wire on a standard K probe)
- T− (screw terminal, K-type thermocouple negative — the red alumel wire. Reversing T+/T− makes the reading FALL as the tip heats, and the input is not isolated, so a grounded-tip probe ties whatever you are measuring to module ground)
Specifications
| Supply voltage | 3.0–5.5 V |
|---|---|
| Thermocouple type | K |
| Measuring range | 0–1024 °C |
| Resolution | 0.25 °C (12 bit) |
| Cold-junction compensation | Built in |
| Interface | SPI read-only (SCK, CS, SO), 4.3 MHz max |
| Conversion time | 0.17 s typical, 0.22 s max |
| Supply current | 0.7 mA typical (1.5 mA max) |
| Fault detection | Open thermocouple flag (bit D2) |
