Abnormal circuit operation detection system

• US 20060242463A1
• Filed: 08/22/2005
• Published: 10/26/2006
• Est. Priority Date: 03/29/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Iwaki, Hiroyuki, Ikeda, Yoshihisa, Hashizume, Masato, Yasui, Takanori, Hashimoto, Chikashi
• Granted Patent: US 7,796,050 B2
• Time in Patent Office: Days
• US Class Current: 714/22
• CPC Class Codes: G01R 31/3004 Current or voltage test

Abstract

An abnormality in operation is detected by meticulously monitoring the operation of a monitored device that comprises a state machine. The state number, indicating the state the monitored device is currently in, is output from the device. The upper and lower limit values of current consumption is set for each state number. A monitoring circuit, using the upper and lower limit values for the present state number, judges the value of current consumption detected by a current detection circuit and detects whether there is abnormality in operation.

Claims

1. An abnormal operation detection system comprising:

a monitored device having a configuration of a state machine in which a plurality of states and conditions for state transitions are defined, said monitored device having a function to output a state number indicating a state of said state machine;

a power consumption detection circuit for detecting power consumption of said monitored device; and

a monitoring circuit for determining the presence or absence of abnormality in said power consumption by using an abnormality evaluation value corresponding to the state number output from said monitored device.

2. An abnormal operation detection system according to claim 1, wherein said monitoring circuit further determines the presence or absence of abnormality in said power consumption by using an accumulated power consumption value, which represents the value of the power consumption accumulated for a predetermined length of time irrespective of said state number, and an abnormality evaluation value predetermined for said accumulated power consumption value.

3. An abnormal operation detection system according to claim 1, further comprising a control circuit for sequentially supplying a plurality of test patterns to said monitored device, and wherein

said monitoring circuit further determines the presence or absence of abnormality in said power consumption by using an abnormality evaluation value corresponding to the test pattern that said control circuit supplies to said monitored device.

4. An abnormal operation detection system according to claim 1, wherein said monitoring circuit has an external storage device for storing an abnormality evaluation value for each state of said monitored device.

5. An abnormal operation detection system according to claim 1, further comprising a temperature sensor for detecting temperature on said monitored device, and wherein

said monitoring circuit further determines the presence or absence of abnormality using an abnormality evaluation value corresponding to the temperature detected by said temperature sensor.