Abstract: A semiconductor integrated circuit includes a memory having bit cells; and a frequency detector outputting a switching signal to switch a test mode from first to second test modes. Further, the memory includes an internal clock generator generating an internal clock in synchronization with the external clock; a writing part writing data into the bit cells based on the internal clock; a delayed clock generator generating a delayed clock by adding a designated delay to the internal clock; a first selector inputting the internal clock and the delayed clock, and, when the frequency of the high-speed clock is less than a designated frequency, selecting the delayed clock based on the switching signal; and a reading part reading the data of the bit cells based on the delayed clock.

Abstract: In a semiconductor integrated circuit device, an n-channel transistor area has an area A on a pad side and an area B on an internal circuit side, where a plurality of protective elements are connected in parallel between a signal line and a power supply line. Each of the protective elements has resistors. Resistance of the resistors in the area A is set higher than resistance of the resistors in the area B by a value corresponding to resistance of parasitic resistance of the signal line included in the area A so that the resistance of the protective elements in the areas A and B are the same or almost the same as each other. A p-channel transistor area has the same configuration as that of the p-channel transistor area.

Abstract: A protection circuit in a semiconductor integrated circuit having a master slice I/O circuit comprises an internal circuit, a pad, and a desired number of protection elements connected in parallel between the internal circuit and the pad. Each protection element includes a P-channel MOS transistor which outputs a first power supply voltage level signal on the basis of an output signal of the internal circuit, a N-channel MOS transistor which outputs a second power supply voltage level signal on the basis of the output signal of the internal circuit, a resistor connected between a signal line connected to the pad and an output terminal of the P-channel MOS transistor, and a resistor connected between the signal line and an output terminal of the N-channel MOS transistor.

Abstract: A protection circuit in a semiconductor integrated circuit having a master slice I/O circuit comprises an internal circuit, a pad, and a desired number of protection elements connected in parallel between the internal circuit and the pad. Each protection element includes a P-channel MOS transistor which outputs a first power supply voltage level signal on the basis of an output signal of the internal circuit, a N-channel MOS transistor which outputs a second power supply voltage level signal on the basis of the output signal of the internal circuit, a resistor connected between a signal line connected to the pad and an output terminal of the P-channel MOS transistor, and a resistor connected between the signal line and an output terminal of the N-channel MOS transistor.