ADT7475 Datasheet | Analog Devices

FEATURES Controls and monitors up to 4 fans High and low frequency fan drive signal 1 on-chip and 2 remote temperature sensors Extended temperature measurement range, up to 191°C Automatic fan speed control mode controls system cooling based on measured temperature Enhanced acoustic mode dramatically reduces user perception of changing fan speeds Thermal protection feature via THERM output Monitors performance impact of Intel® Pentium® 4 processor Thermal control circuit via THERM input 3-wire and 4-wire fan speed measurement Limit parison of all monitored values Meets SMBus 2.0 electrical specifications (fully SMBus 1.1 pliant) Fully Ro HS pliant GENERAL DESCRIPTION The ADT7475 d BCool controller is a thermal monitor and multiple PWM fan controller for noise-sensitive or powersensitive applications requiring active system cooling. The ADT7475 can drive a fan using either a low or high frequency drive signal, monitor the temperature of up to two remote sensor diodes plus its own internal temperature, and measure and control the speed of up to four fans, so they operate at the lowest possible speed for minimum acoustic noise. The automatic fan speed control loop optimizes fan speed for a given temperature. The effectiveness of the system’s thermal solution can be monitored using the THERM input. The ADT7475 also provides critical thermal protection to the system using the bidirectional THERM pin as an output to prevent system or ponent overheating. FUNCTIONAL BLOCK DIAGRAM SCL SDA SMBALERT SERIAL BUS INTERFACE PWM1 PWM2 PWM3 PWM REGISTERS AND CONTROLLERS (HF AND LF) ACOUSTIC ENHANCEMENT CONTROL AUTOMATIC FAN SPEED CONTROL ADDRESS POINTER REGISTER TACH1 TACH2 TACH3 TACH4 FAN SPEED COUNTER PERFORMANCE MONITORING PWM CONFIGURATION REGISTERS INTERRUPT MASKING INTERRUPT STATUS REGISTERS THERM VCC D1+ D1- D2+ D2- VCCP BAND GAP TEMPERATURE SENSOR VCC TO ADT7475 THERMAL PROTECTION INPUT SIGNAL CONDITIONING AND ANALOG MULTIPLEXER 10-BIT ADC LIMIT...