To keep continuity of count values when switching count modes in an asynchronous counter circuit capable of switching count modes.
In an A/D converting method, between flip-flops 410, three-input and one-output type three-value switching sections 420 (422, 424, 426) are provided, each of which switches three values of non-inverted output Q, inverted output NQ and power supply (Vdd) level of each flip-flop 410. The three-value switching section 420 switches three input signals in accordance with two-bit control signals SW1, SW2 and inputs one selected signal to a clock terminal CK of the post-state flip-flop 410. In accordance with the control signals SW1, SW2, when switching count mode, a count value just before mode switching is initially set and then count processing after mode switching can be started.
COPYRIGHT: (C)2009,JPO&INPIT
Noriyuki Fukushima
Kaichi Nitta
Yasuhiro Yasui
| US5877715 |