| 摘要 |
PURPOSE:To obtain two types of analog output modes simply, by providing an MDB signal switching circuit switching an output in response to an output mode designating bit given from an upper-stage device. CONSTITUTION:When a mode designation bit MDB given from an upper-stage device is zero, a switching circuit 21 outputs the most significant bit MSB of a digital data CPUDATA to a digital/analog converter DAC 11 as it is. Since a driver circuit 23 turns off or on transistors Q1, Q2 in response to the MDB= ''0'', an output of a buffer amplifier 22 is reduced to 0 volt and a positive voltage corresponding to a DACDATA using 0V as a reference is obtained from a buffer amplifier 12. When the MDB=''1'', the level inversion signal of the MSB signal is outputted to a DAC 11 as the MSB signal of the DACDATA to respectively turn on and off the Q1, Q2, and an offset voltage is outputted from the amplifier 22 and an analog signal using this voltage as a reference is obtained. |
