| 摘要 |
PURPOSE:To prevent stationary through current between an electric power source and GND by continuously supplying a clock signal to a function block having a dynamic holding circuit even during testing another function block. CONSTITUTION:During testing function blocks 103, 104 except a function block 102 having a dynamic holding circuit, a separation signal 113 becomes one, and because a transfer gate 111 is ON and a N channel 128 is OFF, a clock signal is supplied to a signal 121 with a ring oscillator constituted out of invertors 108 - 110, further as to input signal of OR.NAND gate 115 the clock signal 121 is only supplied to the block 102 because the signal 121 is more effective than the signal 113. Consequently, because the clock signal in the block 102 is not fixed to one or zero, even at having a dynamic holding circuit in it, danger which the input level becomes medium level and through current between the electric source and GND is realized, can be prevented, and bad influence against quality of the device can be removed. |
