Fan Speed Controller Has Auto Shutdown Feature

For use with brushless dc motors, the TC648 is a switch-mode fan speed controller featuring auto-shutdown and over-temperature fault detection. The device is designed to convert any standard two-wire brushless dc fan into an intelligent fan. Consisting of a pulse-width modulated (PWM) fan speed controllers and an integrated over-temperature detector, the device controls and monitors brushless dc fans of any current or voltage. Low-frequency (30 Hz) PWM fan speed control is said to reduce acoustic noise, extend fan life, and lower average fan operating current. The device's over-temperature detector output is asserted when measured temperature exceeds a maximum limit, indicating a blocked air intake, fan bearing failure, or system thermal runaway. The auto-shutdown feature automatically suspends fan operation when measured temperature is below a user-programmed minimum setting, making the device well-suited for fan control in NLX power supply of PCs. The controller is available in standard 8-pin plastic DIP and SOIC packages.