| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a communication apparatus capable of enhancing reliability in detecting the malfunction of a system clock to be supplied to a communication circuit. <P>SOLUTION: A system clock generation circuit 3 having a CMOS circuit generates a system clock SCK with a frequency f1. A monitoring clock generation circuit 4 with a CMOS circuit generates a monitoring clock WCK with a frequency f2 lower than the frequency f1. A communication control circuit 5 is operated by receiving the supply of the system clock SCK and performs communication with an external device through a bus communication line 2. A clock monitoring circuit 7 monitors relative relationship between the frequency of the system clock SCK and the frequency of the monitoring clock WCK. The clock monitoring circuit 7 determines a malfunction of the system clock SCK when the relative relationship is changed, so as to output a malfunction detection signal Sa. A communication I/F circuit 6 opens the bus communication line 2 when the malfunction detection signal Sa is output. <P>COPYRIGHT: (C)2012,JPO&INPIT |
