JTAG

  Introduction JTAG is an integrated method for testing interconnects on printed circuit boards (PCBs) that are implemented at the integrated circuit (IC) level.   Since its introduction as an industry standard in 1990, JTAG has continuously grown in adoption, popularity, and usefulness—even today, new revisions and supplements to the IEEE Std.-1149.1 standard are being developed and implemented. This document is a brief introduction to the nature and history of JTAG, from its introduction to new extensions in current development. JTAG Technology JTAG is commonly referred to as boundary-scan and defined by the Institute of Electrical and Electronic Engineers (IEEE) 1149.1, which originally began as an integrated method for testing interconnects on printed circuit boards (PCBs) implemented at the integrated circuit (IC) level. As PCBs grew in complexity and density—a trend that continues today—limitations in the traditional test methods of in-circuit testers (ICTs) and bed of nails fixt