Supply voltage detection circuit

摘要

A monitor circuit for supplying a detection voltage reflecting a supply voltage, a reference voltage generation circuit for generating a high-precision reference voltage not depending upon the supply voltage, and a comparator for comparing the detection voltage with the reference voltage and outputting the result of the comparison are provided and, in addition, a controller is provided which is made up of an auxiliary reference voltage generation circuit for generating a low-precision auxiliary reference voltage with less power dissipation and an auxiliary comparator for comparing the detection voltage with the auxiliary reference voltage. The auxiliary reference voltage is set higher than the reference voltage, and when the detection voltage becomes higher than the auxiliary reference voltage to cause the comparison output of the auxiliary comparator to become active, the reference voltage generation circuit is placed in a power-down state, thereby achieving a reduction in current dissipation. <IMAGE>