The ADM1027 dBCOOL controller is a complete systems monitor and multiple PWM fan controller for noise sensitive applications requiring active system cooling. It can monitor 12 V, 5 V, 2.5 V CPU supply voltage, plus its own supply voltage. It can monitor the temperature of up to two remote sensor diodes, plus its own internal temperature. It can measure and control the speed of up to four fans so that they operate at the lowest possible speed for minimum acoustic noise. The automatic fan speed control loop optimizes fan speed for a given temperature. Once the control loop parameters are programmed, the ADM1027 can vary fan speed without CPU intervention.