| 摘要 |
PURPOSE:To insulate an analog value from an external load with a small number of parts by applying the analog signal, which is induced in the secondary side of a pulse transformer, to capacitors respectively through plural photo FETs and applying their charging voltages to an analog circuit. CONSTITUTION:The analog output value of a D/A converter 21 is made into pulses by switching of a switch 22, and these pulses are applied to the primary side of a pulse transformer 23 to induce a pulse signal in the secondary side. This signal is charged to capacitors 25A and 25B by turning on and off FETs 24A and 24B. Thus, the analog value of the converter 21 is insulated from the external load. In this case, since modulating and demodulating circuits for passage of the pulse transformer 23 are omitted, the analog value is insulated from an external load 6 by a simple circuit having a small number of parts. |
