PURPOSE: To easily and inexpensively obtain such a constitution that does not allow VIO to exceed VDD by using a DC voltage source and two or a plurality of pieces of rectifiers connected in common on the anode side and connecting the cathode of one of the rectifiers to the power supply terminal of a microcomputer and that of the other rectifier to a power supply terminal for load.
CONSTITUTION: A voltage VOUT which nearly depends on the Zener voltage of a Zener diode 2 is outputted across the GND terminal 7 and output terminal 6 of a DC voltage source 1. When the electric current I1 flowing to a microcomputer 10 and the other current I2 flowing to a load circuit are equal to or larger than I', the difference between the forward voltage VF1 of a rectifier 9 and the forward voltage VF2 of another rectifier 11 always becomes VF. Therefore, a voltage which is lower than the output of the DC voltage source 1 by the forward voltage of the rectifier 9 becomes the power source VDD to the microcomputer 10 and another voltage which is lower than the output of the voltage source 1 by the forward voltage VF2 of the rectifier 11 becomes the power source VL for load.
TAKASHIMA YOSHINORI
TAKAHASHI MASAKI
NAGAHISA TETSURO
Next Patent: THREE-PHASE MULTIPLEX VOLTAGE TYPE PWM INVERTER