In the smartphone and tablet market space, processors are becoming exceedingly fast, usually consisting of multiple core processors that are running over 1 GHz. Inside these systems, there is not a primary method of cooling, no fans, no way of getting the heat generated by the processor out of the system. The problem becomes not the processor temperatures, but the case temperature, as this poses a potential burn hazard to the user. As shown on this slide, a simple solution would be to glue a temperature sensor onto the device case, but this is not typically done. By gluing a temperature sensor onto the case, the entire device size increases significantly. There is also an assembly difficulty of trying to glue a sensor to the case with only a couple millimeters of clearance and subsequently wiring it back down to the PCB. The typical approach is to use a local temperature sensor on the PCB and use it to approximate case temperature, a very inaccurate method. The system temperature can be and often is dramatically different than the case temperature. This approximation approach does not factor in any of the environmental conditions outside the device. For instance, the external air temperature, the humidity level, whether or not the device is in direct sunlight, or if the device is covered by a protective case. All of these factors have a dramatic effect on the actual case temperature. Using this approach requires greater safety margins, thereby forcing designers to reduce performance power in order to maintain safe operating conditions.