| 摘要 |
PROBLEM TO BE SOLVED: To monitor an inner voltage including a boosted voltage and a negative voltage through a simple arrangement by dividing the differential potential between a boosted voltage and a second voltage or between a first voltage and a negative voltage between first and second potentials and outputting it through an MOSFET which is turned on under a predetermined mode. SOLUTION: An inner voltage generating circuit comprises a booster circuit, a voltage drop circuit and a negative voltage generating circuit. A dividing voltage is determined by the ratio of size between MOSFETs: Q1, Q2. At the time of test operation for monitoring VBB, a test signalϕTT has high level andϕTB has low level. The high levelϕTT employs a power supply voltage VDD when the differential voltage between the power supply voltage VDD and the dividing voltage is higher than the threshold level Vth of an MOSFET: Q4 otherwise employs a boosted voltage. Consequently, a dividing voltage (VDD-VBB)/2 is outputted, as it is, from an external terminal Ai regardless of the threshold level Vth of an MOSFET: Q4.
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