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. An open-collector overtemperature fault output is asserted if the primary control input is driven above the normal control range.
The MIC502 features a low-power sleep mode with a userdetermined threshold. Sleep mode completely turns off the fan and occurs when the system is asleep or off (both control inputs very low). A complete shutdown or reset can also be initiated by external circuitry as desired.
The MIC502 is available as 8-pin plastic DIP and SOIC packages in the -40°C to +85°C industrial temperature range.