ADT7470:  Temperature Sensor Hub and Fan Controller

The ADT7470 controller is a multichannel temperature sensor and PWM fan controller and fan speed monitor for noise sensitive systems requiring active system cooling. It is designed to interface directly to an I₂C bus and control/monitor the fans using a service processor. The aim is to quickly develop systems that are modular and can easily be expanded depending on the system’s cooling requirements. The device can monitor up to ten temperature sensors. It can also monitor and control the speed of four fans so that they operate at the lowest possible speed for minimum acoustic noise. A FULL_SPEED input is provided to allow the fans to be “blasted” to 100% via external hardware control, under extreme thermal conditions or on system startup. An SMBALERTinterrupt communicates error conditions such as fan underspeed, fan failure to the system service processor. Individual error conditions can then be read from status registers over the I₂C bus. In the event of a fan failure condition, any or all PWM outputs can be programmed to automatically adjust to 100% to provide failsafe cooling.