| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the power consumption of an in-vehicle device for a smart entry system which achieves various vehicle controls by the communication with mobile devices held by the users. <P>SOLUTION: In this in-vehicle device for a smart entry system (hereafter, referred to as the in-vehicle device), the authentication thereof with the mobile devices is performed by a microcomputer during the start of the microcomputer, and when the microcomputer transfers to a sleep mode, a facilitated authentication is performed by a communication IC driven according to pulses from a PWM circuit. When a duty ratio is set before the microcomputer transfers to the sleep mode and the pulses are output from the PWM circuit, the microcomputer temporarily transfers to the sleep mode immediately before the next frequency on which the setting of the duty ratio is reflected, and the duty ratio is set by starting immediately before the next frequency. Consequently, the power consumption of the microcomputer, eventually the in-vehicle device, can be reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT |
