| 摘要 |
PURPOSE:To facilitate the diagnosing of an internal logic gate with the minimum diagnosing pins by dividing a highly packaged integrated circuit into several diagnosing blocks to be controlled with a control circuit through a selector provided therebetween. CONSTITUTION:First, when a logic gate of a first diagnosing block 1 is diagnosed, after first to third selectors 4-6 are turned to input terminals (b), (c) and (e) respectively, a diagnosing signal is inputted from an input signal pin P1 and the results of a diagnosis can be observed with an output signal pin P2. Then, when diagnosing the second diagnosing block 2, likewise, after the first to third selectors 4-6 are turned to input terminals (a), (d) and (e), a diagnosing signal is inputted into the second diagnosing block 2 and the results of diagnosis can be observed with the output signal pin P2. Controlling the selectors in this manner enables the common use of an actual signal input/output pin for a diagnosing input/output pin to facilitate the diagnosing of an internal logic gate with the mimimum diagnosing pins. |
