Four channel remote temperature sensor works to -40°C

Called MCP9904, it has advanced features such as resistance error correction as well as beta compensation, the latter to support CPU diodes requiring the BJT/transistor model  – those on 45nm processes, for example.

“Beta compensation eliminates temperature errors caused by low, variable beta transistors common in today’s fine geometry processors,” said Microchip. “The automatic beta detection feature monitors each external diode/transistor and determines the optimum sensor settings for accurate temperature measurements regardless of processor technology. This frees the user from providing unique sensor configurations for each temperature monitoring application.”

Resistance error correction automatically reduces temperature error caused by series resistance allowing greater flexibility in routing thermal diodes, there is a sample-frequency hopping filter, and also automatic diode type detection.

“These enable remote diode temperature measurement up to 100 feet [30m] off-board away from the IC,” said Microchip.

Overall, local accuracy up to ±1°C over -40°C to +65°C is claimed, and remote accuracy of ±1°C to +105°C

The chip has one internal  temperature sensor and will work with up to three external diodes. For fewer channels, the MCP9903 is a similar chip with two external channels, and the MCP9902 has one.

Communication with a host is though SMBus (System Management Bus) or I2C.

For development, there is the ADM00615 evaluation board, whic hlooks like it has the dual-channel MCP9902.

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