Auto mode selector

An auto mode selector for a semiconductor memory device having reference voltage selection switching means connected between a reference voltage pin and an internal reference voltage terminal, for selecting one of CTT and LVTTL in response to a reference voltage selection signal, wherein the improvement comprises input leakage current control means for allowing current to flow through a resistor between a supply voltage source and said reference voltage pin only for a predetermined time period in response to an input leakage current control signal from input leakage current control signal generation means wherein said input leakage current control means includes a MOS transistor connected between said supply voltage source and said resistor and having its gate for inputting said input leakage current control signal from said input leakage current control signal generation means wherein said input leakage current control signal generation means includes:

• a first inverter for inverting a pulse signal from pulse generation means;
• first flip-flop means for latching a twice-inverted power-up signal in response to an output signal from said first inverter;
• a second inverter for inverting said twice-inverted power-up signal;
• a third inverter an output signal from said first flip-flop means;
• and
• a NOR gate for performing a NOR operation with respect to output signals from said second and third inverters and outputting the NORed result as said input leakage current control signal.