Implementation of a fast relative digital temperature sensor to achieve thermal protection in Zynq SoC technology

Abstract

<p>More and more industrial embedded systems are developed to undergo hard environmental conditions, especially high temperatures. To prevent this impact, environmental conditions (e.g. the temperature) could be monitored. Plenty of new industrial designs are built around SoCs, and more especially around the Zynq-7000 introduced by Xilinx in 2011. In fact, monitoring the temperature inside the Zynq has become a challenge. While many applications focused on precision, the application proposed here instead is in an industrial context and aims at detecting a temperature excess as fast as possible to achieve the thermal protection of a logic area of the chip. Most of the digital sensors designed require a calibration to be operational. Such a process is not viable for time to market, and a solution must be found to either lighten it (e.g. by doing a simple 3-points calibration) or simply avoiding it. Instead of measuring the temperature in an absolute way, this paper focuses on detecting if the temperature is above or below a threshold. This work exhibits the implementation of three temperature digital sensors with promising results on Zynq technology. Two of the presented sensors are based on a ring-oscillator and another uses a flip-flop as a sensing element. Results show that a temperature increase can be detected in less than 1ms without any calibration protocol and this sensor was found to perfectly fit the targeted application.</p