| 摘要 |
PROBLEM TO BE SOLVED: To generate different internal power supply voltages with each other at the time of an accelerated test and a non-accelerated test in a semiconductor integrated circuit having an inner step-down circuit. SOLUTION: A semiconductor integrated circuit has such a first voltage characteristic I that in the case where an external power supply voltage VEXT is in a range from a given value V1 to a given value V2, it has little dependence on an internal power supply voltage VINT while keeping a preset voltage VA. If the external power supply voltage VEXT exceeds the given value V2, at the time of a non-accelerated test (at the time of a working margin confirmation test), the circuit exhibits a second voltage characteristic II that is varied from the preset voltage VA depending on the internal power supply voltage. At the time of an accelerated test, a third voltage characteristic III is developed wherein a voltage is varied from a preset voltage value VB, which is higher than the preset voltage VA depending on the internal power supply voltage. Accordingly, at the time of the working margin confirmation test, the internal power supply voltage VINT is continued by virtue of the characteristics I, II, making it possible to guarantee the operation within the voltage range from VA to VB. At the time of the accelerated test, satisfactory voltage acceleration is obtained with the aid of the characteristic III. |
