SENS-MAX31855-K
MAX31855 + thermocouple type K
Carte MAX31855 (SPI) + thermocouple K 1m — mesures -200..+1350°C.
Technical analysis
The MAX31855K digitises a type-K thermocouple with built-in cold-junction compensation and a direct SPI output — the clean building block for reading a high furnace, hearth or injection temperature from a microcontroller. Type K reaches up to +1372 °C, far beyond what any silicon probe (DS18B20, BMP280) can withstand.
Two points of honesty. First, accuracy: the converter's internal ±2 °C adds to the thermocouple wire's own tolerance (class 1 or 2, IEC 60584) — the real error budget is that of the complete chain, not the chip alone. Second, wiring: a thermocouple is sensitive to ground loops and noise; in an electrically noisy environment, galvanic isolation is recommended. The furnace-temperature-to-S7-1200 tutorial illustrates the complete chain.
Verified specifications
Every figure below is sourced from the manufacturer datasheet.
- Thermocouple type
- Type K (MAX31855K variant)
- Range (type K)
- −270 °C to +1372 °C
- Resolution
- 0,25 °C (14-bit signed)
- Internal accuracy (type K)
- ±2 °C (−200 to +700 °C)
- Cold-junction compensation
- built-in (−40 to +125 °C)
- Interface
- SPI (read-only)
References & standards
📄 Official manufacturer datasheet — Analog Devices (ex-Maxim)
Applicable standards
- IEC 60584 — Defines the EMF/temperature function and tolerance classes of the type-K thermocouple. The wire tolerance adds to the converter's internal ±2 °C.