SEMICONDUCTOR INTEGRATED CIRCUIT

摘要

PROBLEM TO BE SOLVED: To prevent the breakage of an internal power supply system circuit by suppressing applying of exceeding external power supply voltage to the internal power supply system circuit which originally has to be supplied with dropped voltage when making an LSI having a voltage dropping circuit enter a test mode. SOLUTION: The internal power supply system circuit is provided with the voltage dropping circuit 11 which receives power voltage inputted to a power terminal 13 from outside to generate the dropped voltage dropped to a fixed potential lower than it, the internal power supply system circuit 16 with output voltage from the voltage dropping circuit as its operation power supply at a normal time, and a control circuit 12 which detects the change of at least 2 stages of power supply voltage inputted to the power terminal as input of a voltage change pattern for entry to the test mode and supplies the power supply voltage inputted to the power terminal as the operation power supply of the internal power supply system circuit in place of the output of the voltage dropping circuit for making the LSI enter the test mode. COPYRIGHT: (C)2005,JPO&NCIPI