VOLTAGE DROP CIRCUIT, INTERNAL POWER SOURCE VOLTAGE LEVEL CONTROL METHOD USING THE SAME, AND ITS SEMICONDUCTOR MEMORY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a voltage drop circuit for preventing reduction in writing speed and malfunction of a memory device and eliminating unnecessary power consumption, and further provide an internal power source voltage level control method utilizing this voltage drop circuit and its semiconductor memory device. SOLUTION: This voltage drop circuit includes: a comparison controller 30 for comparing a reference voltage Vref with a voltage level of an internal power source voltage Vint lowered by a first writing operation of a writing driver in response to a write enable signal WE; and a first switching element 40 which is activated by a first control signal S1 to be output in response to the comparison result and controls the voltage level of the internal power source voltage. Further provided are: control means 50 for generating a second control signal S2 to be activated during a response time period required until the operation of the first switching element 40 from the first writing operation of the writing driver; and a second switching element 60 for supplying the external power source voltage as the internal power source voltage during a time period when the second control signal S2 is being activated.