| 摘要 |
PURPOSE: To match phases of power supplies with one another correctly by providing a polarity change detecting device, which detects a change in the polarity of the power supply or a load. CONSTITUTION: A polarity change detecting device is equipped with a three-bit polarity history register 160, exclusive-OR polarity comparison gates 162, 164 and 166, a change comparison OR gate 168 and a synchronous register 161. The polarity history register 160 stores a preceding sample polarity data for the purpose of comparison. The polarity comparison gates 162, 164 and 166 detect changes of polarities for the individual phases. The change comparison gate 168 combines the detected changes of polarities into a single data bit. The synchronous register 161 is used for synchronizing polarity change data with a clock and holds a change bit active during one clock cycle. According to this constitution, the phases of power supplies can be correctly matched with one another. |
