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

• Uninterruptible power supplies

• Power amplifiers