| 摘要 |
PURPOSE: An input buffer circuit is provided to prevent a current passing from VCC to GND of the input buffer from being generated although the open of the input during an input disable is opened in case when the input buffer is utilized as an input buffer to receive an external interrupt. CONSTITUTION: An input buffer includes a Schmidt trigger NAND circuit block(31) for triggering an input data and an input enable/disable signal, a noise filter(32) for delaying a predetermined period after a rising edge and a falling edge of the input signal so as to remove the noise of the triggered input signal, an AND gate(35) for AND operating the input enable/disable signal and a system clock(clk), a first latch block(36) for outputting a D latch enable signal by latching the AND operated signal and the inverted input enable/disable signal, a second latch block(37) for outputting the noise filtering signal inverted by the D latch enable signal and an edge detection block(39) for selectively detecting the signal buffered by the buffer to buffer the output signals of the second latch block(37) and the edge selection signal(Edge_sel) at the rising edge or the falling edge.
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