Boundary-scan output cell with non-critical enable path

US5319646A · kind A · utility

Assignee

• NCR Corporation · US

Inventors

• David L. Simpson · West Columbia, US
• Wilson E. Smoak · West Columbia, US

Key dates

• Filing date: Sep 18, 1991
• Grant date: Jun 7, 1994
• Expiry date: Sep 18, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R31/318541
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A boundary-scan output cell which includes critical data term and non-critical masking term paths without adding an extra layer of logic. The boundary-scan cell includes a multiplexer, a critical data path which transmits critical data terms, coupled to a first multiplexer input, a sampling circuit which transmits non-critical terms, term circuit coupled to a second multiplexer input, and a non-critical term path which transmits non-critical masking terms, coupled to the shift input of the multiplexer. Non-critical masking terms at the shift input are mimicked at the second input. Provision is also made for a test control circuit and a circuit for monitoring critical and non-critical terms.