The MAX6643LBBAEE+ is an automatic PWM fan-speed controller with overtemperature output in 16 pin QSOP package. It monitors temperature and automatically adjusts fan speed to ensure optimum cooling while minimizing acoustic noise from the fan. Each device measures two temperature locations. It generates a PWM waveform that drives an external power transistor which in turn modulates the fan"s power supply. It monitors temperature and adjust the duty cycle of the PWM output waveform to control the fan"s speed according to the cooling needs of the system. The MAX6643 monitors its own die temperature and an optional external transistor"s temperature. The MAX6643 have nine selectable trip temperatures (in 5°C increments). It includes an overtemperature output and can be used for warning or system shutdown. The MAX6643 also features a FULLSPD input that forces the PWM duty cycle to 100% and feature a FANFAIL output that indicates a failed fan.
Supply voltage range is 3V to 5.5V
Operating temperature range from -40°C to 125°C
Pin-selectable low and high temperature fan threshold
Detect fan failure through locked-rotor output, tachometer output or fan-supply current sensing
Multiple 1.6% output duty cycle steps for low audibility of fan speed changes
Spin-up time ensures fan start
Fan start delay minimizes power supply load at power-up
32Hz pulse width modulation output
Controlled duty cycle rate of change ensures good acoustic performance
