Nxp B.v.

Paul-Henri Pugliesi-Conti

Tom Waayers

Johan Corneel Meirlevede

Vincent Chalendard

Michael Rodat

Herv Vincent

Testing of integrated circuitry, wherein the integrated circuitry includes a flip-flop with an asynchronous input, so that during performance of asynchronous scan patterns, glitches are avoided. Combinatorial logic circuitry delivers a local reset signal to the asynchronous input independent of an assertion of an asynchronous global reset signal. A synchronous scan test is performed of delivery of the local reset signal from the combinatorial logic circuitry while masking delivery of any reset signal to the asynchronous input of the flip-flop. An asynchronous scan test is performed of an asynchronous reset of the flip-flop with the asynchronous global reset signal while masking delivery of the local reset signal to the asynchronous input of the flip-flop.

Testing of asynchronous reset logic

Methods, devices and circuits are provided for protecting secure data from being read during a scan chain output. A plurality of scan flip-flops is coupled in a scan chain, and an input circuit is configured to shift input data to the scan flip-flops. A protection circuit is coupled to the scan flip-flops, and the protection circuit configured to detect scan-in of data from the input circuit to a designated one of the scan flip-flops. Scan-out of data from the designated scan flip-flop is enabled in response to detection of a scan-in of data from the input circuit to the designated scan flip-flop. Scan-out of data from the designated scan flip-flop is prevented in response to no detection of scan-in of data from the input circuit to the designated scan flip-flop.

Circuit for securing scan chain data

A contactless smartcard type integrated circuit needing only two pins for performing a standard ATPG test is disclosed. A scan test may be performed using one pin for the clock and the other pin for the input and input of the scan test data. Additionally, security is enhanced by using an embedded signature generator to avoid observation of the data shifted out.

Secure low pin count scan

A multi-clock system-on-chip (D) comprises i) a core (CE) comprising asynchronous clock domains provided for exchanging test data therebetween, ii) a clock generator unit (CGU) arranged for delivering primary clock signals (clk-clko) for at least some of the clock domains, and iii) clock control modules (CCl-CCo), arranged respectively for defining the functional clock signals from the primary clock signals and from control signals (intended for setting the clock control modules (CCl) in a normal mode allowing test data transmission from the corresponding emitter clock domain to at least one receiver clock domain or a shift mode forbidding such a test data transmission). Each clock control module (CCl) is connected to a synchronization means (SM) arranged for switching it from the shift mode to the normal mode, and to a delay means (DM) arranged for putting back the emitter launch edge of a functional clock signal intended for the emitter clock domain when this clock control module (CCl) is set into the normal mode, in order this emitter launch edge be temporally located before each corresponding receiver capture edge of the clock signals intended for the receiver clock domains to which the emitter clock domain must transmit test data.

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Hermanville sur Mer, France

Paul-Henri Pugliesi-Conti