The MAX6668/MAX6670 remote-junction thermal switches with an internal power transistor drive a cooling fan rated for supply voltages up to +12V and 250mA. These devices measure the temperature of an external P-N junction (typically a diode-connected transistor) and turn on the fan power switch when the remote temperature rises above a factory-programmed threshold. Self-contained and requiring no software development, the MAX6668/MAX6670 are simple "drop-in" fan-control solutions for a variety of systems. The MAX6670 features an open-drain WARN output that goes active when the remote temperature exceeds the factory-programmed fan activation threshold by +15C. The MAX6670 features an open-drain OT output that goes active when the remote temperature exceeds the factory-programmed threshold by +30C. The MAX6668/MAX6670 provide a fan-control input, FORCEON, that allows the fan to be driven externally, regardless of temperature.