| 摘要 |
PURPOSE:To easily test the function of a digital circuit by outputting part or the whole of digital data outputted by a digital circuit from a prescribed number of terminals at the time of a test. CONSTITUTION:An integrated circuit incorporates the digital circuit 10 and D/A converters 12, 13, and 14 which convert digital data from the circuit 10 into an analog signal and output it. Then, NAND circuits 15a-15d, 16a-16d, and 17a-17d as a selecting means select and take out a prescribed number of bits which are part or the whole of digital data supplied from the circuit 10 to the D/A converters 12, 13 and 14 at the time of the test in order. Switches 21-23 outputs the prescribed number of bits led out of the NAND circuits 15a-15d, 16a-16d and 17a-17d from a prescribed number of terminals including at least output terminals 24, 25 and 26 for analog signals as a substitute for an output in no-test mode. This digital data is used to decide whether or not the digital circuit is normal, and the level of the analog signal need not be decided.
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