maxtc - Breakout board for Maxim SPI thermocouple sensors

Submitted by GG on Thu, 03/15/2012 - 10:15
Project Status

maxtc bare pcb The Maxim MAX6675 and the newer MAX31855 thermocouple to SPI interface chips are very popular with electronics enthusiasts because of their extreme ease of use combined with good accuracy.
Both devices however are only available in SMD package making breadboard prototyping very difficult without using a suitable breakout PCB. Standard thermocouple connectors are also not breadboard friendly further aggravating the issue.
maxtc is compatible with both the MAX6675 and the MAX31855 and will break out all the necessary signals to a 2.54mm single row header. It also has a standard thermocouple connector and an option to add a SPI flash rom.

maxtc with thermocouple
assembled maxtc


  • support MAX6675 (VDD=3.3 or 5V) and MAX31855 (only with VDD=3.3V)
  • support for K, T, J, N, and E-Type theromcouples (K-Type only for MAX6675)
  • supports 25xx SPI flash ROM (only with VDD=3.3V)

BOM notes

R1 should be mounted only for MAX6675 and if open thermocouple detection is desired.
U2 any vendor and density 25xx series flash can be used depending on the requirements
U1,P1 the BOM file assumes K-Type thermocouple. For other types, both the MAX31855 and the connector part number should be changed according to the following table:

Type Temp Range U1 P1
K -270 to 1372 MAX31855-KASA+ PCC-SMP-K
T -270 to 400 MAX31855-TASA+ PCC-SMP-T
J -210 to 1200 MAX31855-JASA+ PCC-SMP-J
N -270 to 1300 MAX31855-NASA+ PCC-SMP-N
E -270 to 1000 MAX31855-EASA+ PCC-SMP-E
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