Stmicroelectronics S.a.

Stmicroelectronics (grenoble 2) Sas

Paul Armagnat

Thomas Alofs

Hervé Le-Gall

Philippe Lebourg

Thomas Droniou

Jean-Christophe Pont

Marc Beaujoin

A method for scan-testing of an integrated circuit includes the following steps carried out by the circuit itself: upon powering on of the circuit, watching for bit sequences applied to a use pin configured for receiving serial data from the exterior at the rate of a clock signal applied to a clock pin; configuring the circuit in a test mode when a bit sequence is identified as a test initialization sequence; connecting latches of the circuit in a shift register configuration, and connecting the shift register for receiving a test vector in series from the use pin; switching the transfer direction of the use pin to the output mode for providing to the exterior serial data at the rate of the clock signal; and connecting the shift register for providing its content, as a test result set, in series on the use pin.

Digital circuit testable through two pins

A bit detection event within a read period is characterized by sub-dividing each read period into elementary time intervals. Certain ones of the elementary intervals are selected to for a window and a counting operation for a number of bits detected during the intervals within the window is performed. The elementary time intervals are defined by a difference between a frequency corresponding to the read period and a bit detection timing frequency. The counting result for the intervals in the window over several consecutive read periods is statistically processed. A reduction of an integrated electronic circuit test duration results from limiting the counting operations performed to the selected elementary time intervals.

Method for characterizing a bit detection event

An electronic circuit includes a group of devices which facilitate scan testing of at least one part of the electronic circuit. Those devices include a scan test device. The circuit further includes a state machine which operates to transfer data from an input pin of the circuit which is dedicated to the state machine to the devices relating to scan testing. The state machine supports a plurality of data transfer protocols. The choice of the protocol to be used is made as a function of a signal received on the input pin. Responsive to an input pin signal, the state machine enters an operational mode wherein scan test programming data is serially received at the input pin and communicated to the devices which facilitate scan testing. More specifically, the scan test programming data is serially communicated to a scan test register, where the data is output in parallel to the scan test device.

Scan test circuitry using a state machine and a limited number of dedicated pins

The sequential access memory array is able to store p words each of n bits. Such p test words each made up of n test bits are written in the memory array, the p test words are extracted sequentially and, for each current word extracted, the n test bits that compose it are compared sequentially with n respective expected data bits before extracting the next test word.

Growing community of inventors

Seyssinet, France

Paul Armagnat