Maximum operating voltage (VMAX) limit for SOCs in thin form factor mobile devices with touch sensitive displays

Proximity to the touch sensitive display in thin form factor mobile devices puts a stringent upper limit on the temperature (and hence the VMAX) at which the SOC may be operated, making the industrial design sometimes limited by the thermals, rather than reliability. The tradeoff between the VMAX and the distance between the SOC and the touch display (Zht) is systematically explored. A simple analytical framework which addresses tradeoffs among different key parameters of interest (both thermal and reliability) is developed. It is emphasized that by carefully optimizing the time for which the SOC operates at VMAX, and/or by de-emphasizing SOC domain areas operating under lower VMAX, the Zht may be scaled down, enabling efficient thermal solution design, without compromising performance, while maintaining constant reliability risk.