MAX6661

V_CC, ALERT, OVERT ............................................-0.3V to +6V
VFAN, TACH IN, FAN .........................................-0.3V to +16V
DXP, CS, SDOUT, GAIN, SCL, SDIN..........-0.3V to (V_CC + 0.3V)
DXN ....................................................................-0.3V to +1V
SDOUT Current................................................-1mA to +50mA
DXN Current ..................................................................±1mA
FAN Out Current ..........................................................500mA
Continuous Power Dissipation (T_A = +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C).........667mW
Operating Temperature Range ................. -40°C to +125°C
Junction Temperature ................................................+150°C
Storage Temperature Range ......................-65°C to +150°C
Lead Temperature (soldering, 10s) ............................+300°C

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The MAX6661 is a remote temperature sensor and fanspeed regulator that provides complete closed-loop fan control. The remote temperature sensor is typically a common-collector PNP, such as a substrate PNP of a microprocessor, or a diode-connected transistor, typically a low-cost, easily mounted 2N3904 NPN type or 2N3906 PNP type.

The MAX6661 also incorporates a closed-loop fan controller that regulates fan speed with tachometer feedback.The MAX6661 compares temperature data to a fan threshold temperature and gain setting, both programmed over the SPI™ bus by the user. The result is automatic fan control that is proportional to the remotejunction temperature. The temperature feedback loop of MAX6661 can be broken at any time for system control over the speed of the fan.

Fan speed of MAX6661 is voltage controlled as opposed to PWM controlled, greatly reducing acoustic noise and maximizing fan reliability. An on-chip power device drives fans rated up to 250mA.

Temperature data is updated every 500ms and is readable at any time over the SPI interface. The MAX6661 is accurate to 1°C (max) when the remote junction is between +60°C to +100°C. Data is formatted as a 10-bit + sign word with 0.125°C resolution.

The MAX6661 is specified between -40°C to +125°C and is available in a 16-pin QSOP package.