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Thermostat EEM

4-channel temperature controller.

Design files (schematics, PCB layouts, BOMs) can be found at Thermostat_EEM/Releases.

Overview

• TEC Channel count: 4

• Sensor Channel count: 8 differential, 16 single-ended

• Supported sensors: read by AD7172-2 ADC

  • symmetric two-, four-, or six-wire ratiometric (10k NTC) - 8 channels
  • single-ended two-, three-, or five-wire ratiometric (10k NTC) - 16 channels
  • four-wire or six-wire bridge - 8 full bridges with excitation and reference sense shared in pairs
  • special NTC/RTD configurations (e.g. bridge differential)
  • cryogenic diode (requires a precise current source)

• Load (heater/TEC) drive:

  • up to 8W (+/-2A with 4V compliance) from MAX1968 drivers;
  • up to 16W (+4A 4V) from MAX1969 drivers

• Form factor: 3U module

• Output connectors: Sensor and load connect via HD44 DSUB connector; DSUB to terminal block adapter is included by default.

• Programming interface: Ethernet via RJ45 connector on the front panel. USB via the micro USB connector on the front panel. EEM connector with SPI and GPIO

• Indicators 8 front panel LEDs

• Power supply:

  • +12V DC (4A max) supplied either by a rear Molex or barrel connector,
  • EEM - internal 100mils pin-header,
  • PoE via onboard 30W Silvertel AG5300 module. Note that TEC driver maximum sum power capability cannot be achieved with PoE supply
  • Active total power sum monitoring and management
  • Active module temperature monitoring and management

• Microprocessor: STM332F427ZI

Board render

Firmware

• Thermostat-EEM firmware developed by QUARTIQ

Previous Versions

Thermostat_Thorlabs: Based on a Thorlabs temperature control module. The Thorlabs module has a poor tempco and can't drive resistive heaters so that approach was scrapped in favor of this one (see issue #4).

Thermostat v1: Prototype version based on a different microprocessor

Thermostat v2: 2 channel version