| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To accurately determine that a high state of an input signal changes to a low state when an external power supply voltage is lowered, in an electronic controller having a function of boosting the external power supply voltage via a boosting circuit to generate an operating voltage for a microcomputer. <P>SOLUTION: In an on-board electronic controller having a function of boosting a battery voltage (hereinafter referred to as VB) to generate the operating voltage of the microcomputer, a switch signal, which is set at VB as a high state when the switch is turned on and is set at a ground voltage as a low state when the switch is turned off, is used as an input signal. Then, the microcomputer detects the input signal and VB with a built-in A/D converter (S210, S220), and sets a threshold value Y for determining that the input signal changes from "high" to "low" to be a lower value as a detection value becomes lower according to the detection value of VB (S270). Additionally, the microcomputer, when determining that the detection value of the input signal≤the threshold value Y, takes the determination result of the input signal as "low" (S280). <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
