The present disclosure describes novel methods and apparatuses for directly accessing JTAG Tap domains that exist in a scan path of many serially connected JTAG Tap domains. Direct scan access to a selected Tap domain by a JTAG controller is achieved using auxiliary digital or analog terminals associated with the Tap domain and connected to the JTAG controller. During direct scan access, the auxiliary digital or analog terminals serve as serial data input and serial data output paths between the selected Tap domain and the JTAG controller.

A semiconductor integrated circuit includes scan chains, each of which includes a serial connection of sequential circuits and performs a shift register operation in a scan test; and an integrated clock gating (ICG) chain composed by coupling, to one another, ICG circuits, each of which individually supplies a corresponding one of the scan chains with a circuit clock signal to operate the sequential circuits. In the ICG chain, an ICG enable propagation signal for controlling timing when the ICG circuits output the circuit clock signals propagates through a signal line and is input sequentially to the ICG circuits. The ICG circuits output the circuit clock signals at respective timings that are different among the scan chains.

A semiconductor device comprises a plurality of memory elements, test control circuitry, and a testing interface. The test control circuitry is configure to determine that one or more clock signals associated with the memory elements have been stopped and generate a scan clock signal based on the determination that the one or more clock signals have been stopped. The test control circuitry is further configured to communicate the scan clock signal to the memory elements. The testing interface is configured to communicate test data from the memory elements. In one example, the test data is delimited with start and end marker elements. The semiconductor device is mounted to a circuit board and is communicatively coupled to communication pins of the circuit board.

A circuit comprises a plurality of clock control devices. Each of the clock control devices is configured to generate a scan test clock signal for a particular clock domain in the circuit and comprises circuitry configured to select clock pulses of a fast clock signal as scan capture clock pulses for the particular clock domain based on a particular clock pulse of a slow clock signal and a scan enable signal. The order and spacing between the groups of the scan capture clock pulses for different clock domains correspond to the order and spacing of the clock pulses of the slow clock signal.

During functional/normal operation of an integrated circuit including multiple independent processing elements, a selected independent processing element is taken offline and the functionality of the selected independent processing element is then tested while the remaining independent processing elements continue functional operation. To minimize voltage drops resulting from current fluctuations produced by the testing of the processing element, clocks used to synchronize operations within each partition of a processing element are staggered. This varies the toggle rate within each partition of the processing element during the testing of the processing core, thereby reducing the resulting voltage drop. This may also improve test quality within an automated test equipment (ATE) environment.

An Integrated Circuit (IC) includes a storage element and control circuitry. The control circuitry is configured to select, responsively to a scan-enable control, between a functional-data input and a scan-data input to serve as an input to the storage element, to selectively disable toggling of an output of the storage element, responsively to a clock-enable control, by gating a clock signal provided to the storage element, and, while the clock-enable control indicates that the output of the storage element is to be disabled from toggling, to select the input of the storage element to be the scan-data input.

Testing clock division circuitry includes generating pseudo random test pattern bits for scan chain logic in programmable clock division logic circuitry and divided clock counter circuitry. A shift clock is used to shift the test pattern bits into the scan chain logic. A capture clock signal is used in the programmable clock division logic during a non-test mode of operation. The shift clock is used to provide output shift bits from the scan chain logic to a multi-input shift register (MISR). Once all the output shift bits for the test pattern bits are provided to the MISR, a final test signature from the MISR is compared to an expected test signature to determine whether the programmable clock division logic circuitry and divided clock counter circuitry are free of faults.

An integrated circuit includes a data propagation path including a flip-flop. The flip-flop includes a first latch and a second latch. The integrated circuit includes a third latch that acts as a dummy latch. The input of the third latch is coupled to the output of the first latch. The integrated circuit includes a fault detector coupled to the output of the flip-flop and the output of the third latch. The third latch includes a signal propagation delay selected so that the third latch will fail to capture data in a given clock cycle before the second latch of the flip-flop fails to capture the data in the given clock cycle. The fault detector that detects when the third latch is failed to capture the data.

This disclosure describes die test architectures that can be implemented in a first, middle and last die of a die stack. The die test architectures are mainly the same, but for the exceptions mentioned in this disclosure.

An integrated circuit for transition fault testing comprises a synchronizing circuit including a first set of shift registers coupled to receive a scan enable signal and to provide a synchronizing signal based on the scan enable signal; a clock leaker circuit coupled to the synchronizing circuit and including a second set of shift registers coupled to receive a first clock signal based on the synchronizing signal and to provide a second clock signal that includes a set of pulses; and a multiplexer (MUX) that includes a first input coupled to receive a shift clock, a second input coupled to the clock leaker circuit to receive the second clock signal, and an output configured to provide an output clock signal that includes a second set of pulses.