POWER SUPPLY VOLTAGE DETECTING CIRCUIT

摘要

PURPOSE:To attain low power consumption by utilizing a drain current characteristic of an MOSFET, comparing a voltage subject to level shift of a power supply voltage with a prescribed voltage and detecting a power supply voltage to eliminate the need for an externally mounted resistor and a resistor split circuit. CONSTITUTION:The 1st power voltage division circuit is constituted by connecting in series an enhancement MOSFET-TR1 and a depletion MOSFET-TR2 are connected in series in opposite direction as above to constitute the 2nd power supply voltage dividing circuit. A voltage V1 shifting the level by a prescribed voltage from the power supply voltage and a prescribed voltage V2 independently of the power supply voltage are obtained by utilizing the drain current characteristic. Then the power supply voltage is detected by applying the voltages V1, V2 to both inputs of a comparator 1 and comparing them.