Micrel Semiconductor Inc. (San Jose, CA) introduced the MIC502 fan control IC, which is designed for NLX and ATX power supplies. The device has two control inputs that can be used as thermistor or voltage control inputs. The higher of the two sets the duty cycle of the signal from the PWM output.
The IC can operate from the same 12V supply used by the fan and is designed for fully ratiometric temperature sensing. The MIC502 operates on a 4.5V to 13.2V supply range, and provides high current output of 10mA.
The device is available in 8-pin DIP or SOIC packages for $1.20 in 1,000-piece quantities.