Microchip Technology Inc.’s MCP9805 digital temperature
sensor converts temperatures between -40°C and
+125°C to a digital word. This sensor is designed to
meet the JEDEC standard JC42.4 for Mobile Platform
Memory Module Thermal Sensor. This device provides
an accuracy of ±1°C (max.) from a temperature range
of +75°C to +95°C (active range) and ±2°C (max.) from
+40°C to +125°C (monitor range) as defined in the
JEDEC standard.
The MCP9805 comes with user-programmable
registers that provide flexibility for DIMM
temperature-sensing applications. The registers allow
user-selectable settings such as Shutdown or
Low-Power modes and the specification of temperature
event and critical output boundaries. When the
temperature changes beyond the specified boundary
limits, the MCP9805 outputs an Event signal. The user
has the option of setting the Event output signal polarity
as either an active-low or active-high comparator
output for thermostat operation, or as a temperature
event interrupt output for microprocessor-based
systems. The Event output can also be configured as a
critical temperature output.
This sensor has a 2-wire industry-standard SMBus
and Standard mode I2C compatible (100 kHz bus
clock) serial interface protocol, allowing up to eight sensors
to be controlled in a single serial bus. These features
make the MCP9805 ideal for sophisticated
multi-zone temperature-monitoring applications.