MCP9902 Remote Temperature Sensors

MCP9902 Remote Temperature Sensors

Microchip's MCP9902 is a high-accuracy, low-cost, system management bus (SMBus) temperature sensor. Advanced features such as resistance error correction (REC), beta compensation (to support CPU diodes requiring the BJT / transistor model including 45 nm, 65 nm, and 90 nm processors), and automatic diode type detection combine to provide a robust solution for complex environmental monitoring applications.

The MCP9902 monitors two temperature channels (one external and one internal). It provides ±1°C accuracy for both external and internal diode temperatures.

Resistance error correction automatically eliminates the temperature error caused by series resistance, allowing greater flexibility in routing thermal diodes. Beta compensation eliminates temperature errors caused by low, variable beta transistors common in today's fine geometry processors. The automatic beta-detection feature monitors the 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. These advanced features plus ±1° measurement accuracy provide a low-cost, highly flexible and accurate solution for critical temperature monitoring applications.

The MCP9902 temperature sensor evaluation board provides the means to demonstrate all of the MCP9902 features, and allows a user to view and modify registers. A user may plot the temperature of the two temperature channels and set alert temperatures associated with those channels. LEDs indicating status information and test points are included to enable system voltage monitoring, using a voltmeter or an oscilloscope. The board requires only one universal serial bus (USB) connection to power it. The USB-to-SMBus bridge regulates the +5 V USB power to +3.3 V used by the MCP9902 and other evaluation board circuitry.

  • Programmable SMBus address
  • Support for diodes requiring the BJT / transistor model
    • Supports transistor and diode model CPU thermal diodes
  • Automatically determines external diode type and optimal settings
  • External temperature monitors
    • ±1°C accuracy (-40°C <>DIODE <>
    • 0.125°C resolution
    • Supports up to 2.2 nF diode filter capacitor
  • Automatically determines external diode type and optimal settings
  • Resistance error correction
  • Internal temperature monitor
    • ±1°C accuracy
    • 0.125°C resolution
  • 3.3 V supply voltage
  • Programmable temperature limits for ALERT# and THERM#
  • Available in a small, 8-pin, 2 mm x 2 mm, WDFN, RoHS-compliant package
  • Remote radio units
  • Base stations
  • Industrial
  • Industrial freezers
  • Food preparation