| 摘要 |
PROBLEM TO BE SOLVED: To determine the average value of a switching current passing through a coil easily and appropriately. SOLUTION: A current passing through a coil under measurement increases when a pulse signal PS is at a high level. A voltage corresponding to the instantaneous value of the current passing through the coil is input to an input terminal IN. A blanking signal generating circuit 23 generates a signal S1 having a predetermined pulse width rising in sync with the rise of the pulse signal PS. While the signal S1 is at the high level, a switch 11 is turned on to make a capacitor 12 maintain the voltage at the input terminal IN. A switch 17 is turned on to connect a capacitor 18 to a connection point n1 of resistors 15, 16 when the switch 11 is turned off and detaches the capacitor 18 from the connection point n1 when the pulse signal PS reaches a low level. The capacitor 18 is charged with a voltage corresponding to the average value of an increase in the current passing through the coil. A voltage obtained by adding the charging voltage of the capacitor 12 to the charging voltage is supplied to a capacitor 21. COPYRIGHT: (C)2007,JPO&INPIT
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