Patent number 8786304 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "This is related to a semiconductor device having a function, for limiting (cutting) the power supply of an internal circuit.
"Inclusion of a function of partially limiting (cutting) the power supply of an internal circuit, namely, a so-called power gating function, in large-scale integrated circuits (LSIs) to decrease the power consumption is becoming the mainstream. On the other hand, LSIs have a plurality of test circuits for use in a test of the LSIs. More specifically, the LSIs have circuits, such as an input/output test circuit that performs fault diagnosis of data writing/reading circuits and an accelerated test circuit that performs an accelerated test on internal circuits of the LSIs.
"An input/output test circuit includes a circuit that serially couples, in series like a chain, flip flops related to writing and reading of an LSI and a control circuit that receives control signals and test data from outside of the LSI and controls the state of the test (see, for example, Japanese Laid-open Patent Publication No. 2003-98223). In addition, an accelerated test circuit includes a circuit that applies an accelerated test voltage to an internal circuit and a control circuit that receives control signals from outside of an LSI and controls the state of the test (see, for example, Japanese Laid-open Patent Publication No. 10-21699).
"A test of an LSI having a control circuit that performs a power gating operation and a control circuit that controls the state of the test has to be carried out while allowing the control circuits to operate in cooperation with each other. However, sending a control signal for permitting the cooperation between the control circuits to an LSI from a testing equipment residing outside of the LSI requires an expensive testing equipment having an advanced function, which thus increases the cost for the test.
"Nevertheless, when the expensive testing equipment that generates a control signal for permitting the cooperation between control circuits does not employed and the control circuit that performs the power gating operation and the control circuit that controls the state of the test do not operate in cooperation with each other, the following disadvantages may occur. At the time of an accelerated test, application of a sufficient level of stress, which is carried out by applying a predetermined voltage level to an internal circuit, is not achieved because the power gating function is not cancelled. Additionally, at the time of an input/output test, test data is not transferred since an unexpected power gating operation is activated. As a result, the accelerated test or the input/output test may be undesirably prevented."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "According to one aspect of embodiments, a semiconductor device described bellow is provided. A semiconductor device including a first power line, a second power line, a signal line, a switch for selecting coupling of the first power line to the second power line or isolation of the first power line from the second power line according to a driving state of the signal line, a switching circuit for switching the driving state of the signal line, and a first control circuit for outputting a second signal to the switching circuit, wherein the switching circuit drives the signal line to couple the first power line to the second power line or to isolate the first power line from the second power line according to a logical value of the second signal when a first signal making an operational state of the semiconductor device switch between a test state and a normal operational state is set to a first logical value, whereas the switching circuit drives the signal line to couple the first power line to the second power line when the first signal is set to a second logical value."
URL and more information on this patent, see:
Keywords for this news article include: Electronics, Semiconductor,
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