Power-aware Test Scheduling for IEEE 1687 Networks with Multiple Power Domains

Abstract

New test access methodologies are required to cope with the ever-increasing complexity of latest system-on-a-chip designs. The IEEE 1687 standard defines an access methodology to embedded instruments through a reconfigurable scan infrastructure. This technique allows implementing even large networks while keeping the individual access time low since only relevant parts of the scan chain are included in the scan path. However, the reconfiguration introduces a timing overhead, which can be mitigated by accessing instruments concurrently. The concurrent activation of instruments forms a critical aspect from the power management perspective since latest designs consist of multiple power domains with individual power constraints. To avoid any test failures, it must be avoided that the total power consumption of the concurrently activated instruments exceeds the domain’s power limit. Particularly when considering highly complex IEEE 1687 networks, which reveal the full potential of the standard by introducing hierarchical and optimized networks, the power-aware test scheduling is a non-trivial task.This paper proposes a test scheduling scheme for complex IEEE 1687 networks, which heavily orchestrates graph-based methods. In the end, an optimized test plan is determined, which ensures, on the one hand, a minimized overall test access time and, on the other hand, full compliance with the given power constraints. The approach’s efficacy is demonstrated on state-of-the-art benchmark sets involving complex networks with various power domains.