| 摘要 |
PROBLEM TO BE SOLVED: To monitor a plurality of power supplies as monitored power supplies, with regard to a power supply monitoring circuit which monitors the driver power supply of a switching element as a monitored power supply. SOLUTION: The power supply monitoring circuit VP, which monitors the power supplies VH1, VL of drivers GD1, GD2 corresponding to the switching elements (Q1, Q2) between a high side and a low side, is equipped with a capacitor C11 which is charged from a power supply (VL) different from a monitored power supply (VH1) via a resistor R11 and discharges on the monitored power supply (VH1) via a diode D10 and a resistor R1 when the monitored power supply is lowered in voltage, and with a comparison means (CMP) which compares the terminal voltage of the capacitor C11 with a reference value and outputs an alarm signal when the terminal voltage is lowered than the reference value due to the discharge of the capacitor C11 caused by the voltage drop of the monitored power supply. COPYRIGHT: (C)2009,JPO&INPIT
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