Power-efficient control of thermoelectric coolers considering distributed hot spots

Thermoelectric coolers are compact devices that can target hot spots on a VLSI die. These devices are connected electrically in series and controlled together, i.e., all are ON or OFF at the same time. However, spatial and temporal distributions of hot spots on a VLSI die are non-uniform, and therefore, activating all of TECs to address one or a few localized hot spots is not economical. This traditional technique indeed leads to a significant power waste. This paper suggests that adjacent hot spots with the same thermal behavior can be grouped and controlled by a cluster of TECs. A bypass switch for each TEC cluster is added in order to allow selectively turning OFF some TEC clusters which are needed. More precisely, a clustering problem is formulated which aims to minimize the power waste due to excessive use of TECs. Due to the large number of variables in problems of interesting sizes, a greedy heuristic method for solving the problem is introduced. It is shown that the proposed heuristic can reduce the wasted power on average by 81% and also decrease the total TEC power consumption on average by 42%.