MAX6660AEE+ (MAXIM INTEGRATED PRODUCTS)

The MAX6660AEE+ is a remote-junction temperature-controlled fan-speed regulator with SMBus interface in 16 pin QSOP package. The remote temperature sensor is 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. It incorporates a closed-loop fan controller that regulates fan speed with tachometer feedback. It compares temperature data to a fan threshold temperature and gain setting, both programmed over the SMBus by the user. The result is automatic fan control that is proportional to the remote junction temperature. The temperature feedback loop can be broken at any time for system control over the speed of the fan. Fan speed is voltage controlled as opposed to PWM controlled, greatly reducing acoustic noise and maximizing fan reliability. Temperature data is updated every 0.25s and is readable at any time over the SMBus interface.