| 摘要 |
<P>PROBLEM TO BE SOLVED: To maintain a stop state of a microcomputer when the microcomputer is in the stop state and power source voltage is supplied to the microcomputer by a capacitor. <P>SOLUTION: A detection circuit (3) includes: an external capacitor discharge circuit (30A) for discharging an external capacitor (C1); an internal capacitor (C2) for holding power source voltage; an internal capacitor discharge circuit (30) for discharging the internal capacitor (C2); a comparator (32); and an output circuit (33). The comparator (32) compares first voltage (V<SB POS="POST">C1</SB>) of the external capacitor (C1) after discharge with second voltage (V<SB POS="POST">C2</SB>) of the internal capacitor (C2) after discharge. When the first voltage (V<SB POS="POST">C1</SB>) is lower than the second voltage (V<SB POS="POST">C2</SB>) as a result of the comparison, the output circuit (33) outputs a detection signal (S2) showing that the microcomputer receives supply of power source voltage from the external capacitor (C1). An interruption circuit (4) does not output an interruption signal (SI) when receiving the detection signal (S2). <P>COPYRIGHT: (C)2013,JPO&INPIT |
