OUTPUT LEVEL CONVERSION APPARATUS OF ANALOG/DIGITAL CONVERSION CIRCUIT

摘要

PURPOSE: An output level conversion apparatus of an analog/digital conversion circuit is provided, which selects an input analog signal of an A/D conversion unit using a switching device. CONSTITUTION: A decoder(20) decodes a control signal transmitted from a central processing unit(10), and an inverter(30) inverts a signal decoded in the decoder and outputs it. A light emitting diode(LED)(41) is turned on with a signal being output from the inverter. A switching device(40) is combined to a light detection transistor(42) detecting a light emitted from the LED. Thus, the DC level conversion circuit converts a level of the control signal from the central processing unit for it to be used as an input analog selection signal of the A/D conversion unit.