The ADT74701 controller is a multichannel temperature sensor and PWM fan controller and fan speed monitor for systems requiring active cooling. It is designed to interface directly to an I2 C? bus. The ADT7470 can monitor up to 10 daisy-chained TMP05 temperature sensors. It can also monitor and control the speed of four fans， in automatic or in manual control loops. A FULL_SPEED input is provided to allow the fans to be blasted to maximum speed， via external hardware control， under extreme thermal conditions or on system startup. An SMBALERT interrupt communicates error conditions such as fan under speed and over temperature measurements to the system service processor. Individual error conditions can then be read from status registers over the I2 C bus.