LSI WITH BUILT-IN STORAGE

摘要

PROBLEM TO BE SOLVED: To provide a LSI with built-in storage which can surely detect the breakdown of a transistor in a decoder by an operation test. SOLUTION: A selector 302 outputs a clock signal CLK-2 as the selector- output signal CO when a test signal TEST is 1. When a reset signal RESET becomes 1 in this state, a 3-bit counter 300 consecutively increments a counter- output signal T1 from '000' to '111' with synchronizing with the startup edge of the clock signal CLK-2. At that time, the signal '111' is certainly inputted in 3-input NAND gates 310-317 just before the signal '011', '101' or '110' is inputted. Accordingly, each of the output terminals of 3-input NAND gates 310-317 is discharged every inputting, and therefore the state of the prior output can not be kept as it is even if a parasitic capacity exists.