General Description
The MIC502 is a thermal and fan management IC which supports the features for NLX/ATX power supplies and other control applications.
Fan speed is determined by an external temperature sensor, typically a thermistor-resistor divider, and (optionally) a second signal, such as the NLX “FanC” signal. The MIC502 produces a low-frequency pulse-width modulated output for driving an external motor drive transistor. Low-frequency PWM speed control allows operation of standard brushless dc fans at low duty cycle for reduced acoustic noise and permits the use of a very small power transistor. The PWM time base is determined by an external capacitor.

FEATUREs
• Temperature-proportional fan speed control
• Low-cost, efficient PWM fan drive
• 4.5V to 13.2V IC supply range
• Controls any voltage fan
• Overtemperature detection with fault output
• Integrated fan startup timer
• Automatic user-specified sleep mode
• Supports low-cost NTC/PTC thermistors
• 8-pin DIP and SOIC packages

APPLICATIONs
• NLX and ATX power supplies
• Personal computers
• File servers
• Telecom and networking hardware
• Printers, copiers, and office equipment
• Instrumentation
• Uninterruptable power supplies
• Power amplifiers