| 摘要 |
PURPOSE:To obtain an IC device which can evaluate the characteristics of a function circuit without using any pins exclusive for a test. CONSTITUTION:When a signal ''1'' is applied to a pin T1R in synchronism with the energization of a power source, a latch circuit 16 is reset, and produced an output ''0''. At this time a decoder 17 produces a signal ''1'', a function circuit 19 is set through an OR gate 18 to a normal mode, and an IC is ordinarily operated. When a pulse having a frequency larger than a pin Ia is applied to a pin Ib in this state, a binary counter 14 repeates ''0'' or ''1'', the latch circuit 16 stores the counted value, the signal ''1'' of the decoder 17 is fed to and resets the binary counter 14 via the gate 15, and the signals of the pins Ia, Ib can be used for the input signal. When a pulse signal of high frequency is applied to the pin Ia, the decorder selects a test mode, a function circuit 19 will dispatch a signal with this output, and performs the characteristic test of the corresponding function block. When the signal is again applied to the pin T1R, it returns to the normal mode, and no pin exclusive for the test is necessary. |
