View max6665 datasheet:

19-2056; Rev 0; 5/01 Fan Controller/Driver with Factory- Programmed Temperature Thresholds General Description Features The MAX6665 is a fully integrated thermal switch with ¦ On-Chip 250mA Fan Switch an internal power transistor for driving a cooling fan ¦ No External Components Required rated up to 24V and 250mA. When the MAX6665’s tem- perature rises above a factory-programmed threshold, ¦ Factory-Programmed Thresholds the FANOUT pin becomes active and powers the fan. ¦ Two Overtemperature Warning Signals The MAX6665 is available with factory-programmed fan activation threshold temperatures from +40°C to +70°C ¦ Pin-Selectable 1°C, 4°C, and 8°C Hysteresis in 5°C increments. Accuracy of the fan activation trip ¦ Low 65µA Supply Current point is ±1°C (typ) and ±3°C (max)