Semiconductor storage device having synchronous and asynchronous modes
AssigneeFreescale Semiconductor, Inc.
InventorsJORGE CORSO, MARCOS C. BARROS, ALEXANDRE S. LUJAN
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Abstract
A method for performing scan testing using a scan chain having a plurality of storage elements is described. During a capture phase, each storage element of the scan chain stores data from a first data input of the storage element synchronously to a clock signal. And during a shift phase, a scan pattern is shifted into the scan chain in which each storage element stores data from a second data input of the storage element asynchronously with to the clock signal.
Claims20
A method for performing scan testing using a scan chain having a plurality of storage elements, the method comprising:
- during a capture phase, each storage element of the scan chain storing data from a first data input of the storage element synchronously with a clock signal;
- and
- during a shift phase, shifting a scan pattern into the scan chain in which each storage element stores data from a second data input of the storage element asynchronously with the clock signal.
An integrated circuit comprising:
- a scan test controller having a clock output configured to provide a clock signal, a request output configured to provide a request signal, and scan data output configured to provide scan patterns;
- and
- a scan chain having a plurality of storage elements includes a first storage element, a last storage element, and one or more intermediate storage elements between the first and last storage element, wherein each storage element includes a data input, a scan data input, a clock input, a request input, a data select input, a data output, and a storage complete output, wherein:
- the scan data input of a first storage element of the scan chain is coupled to receive a scan pattern bit from the scan test controller and the storage complete output of the first storage element is coupled to provide an acknowledge signal at the storage complete output to the scan test controller,
- the request input of a last storage element of the scan chain is coupled to receive the request signal from the scan test controller, and the data output of the last storage element is coupled to provided scan data output to the scan test controller, and
- for each intermediate storage element, the scan data input is coupled to a data output of a preceding storage element, the data output is coupled to a scan data input of a succeeding storage element, the request input is coupled to a storage complete output of the succeeding storage element, and the storage complete output is coupled to a request input of the preceding storage element.
A storage element having a synchronous mode and an asynchronous mode, comprising:
- a first data input;
- a second data input;
- a clock input;
- a request input coupled to receive a storage request;
- a storage complete output coupled to provide a storage complete indicator;
- and
- a data output, wherein:
- during operation in the synchronous mode, data values from a selected one of the first data input or second data input are stored into the storage element and provided at the data output synchronous to a clock signal at the clock input, and
- during operation in the asynchronous mode, storage of an input data value at a selected one of the first data input or second data input into the storage element is initiated in response to assertion of the storage request, and in response to completing storage of the input data value into the storage element, the storage complete indicator is asserted.
Dependencies are inferred from the claim text.