Semiconductor memory

Abstract

A semiconductor memory device having a memory array is provided. A read unit reads information stored in a memory cell. A step-up unit steps up an externally supplied voltage, and supplies the stepped-up voltage to the memory cell. A start control unit has the step-up unit start the stepping up after a read cycle begins. A detection unit detects that the stepped-up voltage has reached a predetermined level, and has the read unit start the reading upon the detection. A stop control unit has the step-up unit stop the stepping up when a time period required for the reading has elapsed since the detection. With this construction, the time taken for stepping up the voltage supplied to the memory cell is minimized in accordance with the time taken for the reading. Hence the current consumption is reduced when compared with the case where the step-up time is set unnecessarily long.

Description

technical field [0001] The present invention relates to a semiconductor storage device, and in particular to low current consumption technology of a semiconductor storage device having a readout circuit with a built-in boost power supply circuit. Background technique [0002] As one of the readout methods of a semiconductor memory device mounted on a microcomputer device, generally, one of a plurality of memory cells arranged in a matrix is ​​selected by a word line and a bit line, and the selected memory cell is read from the selected memory cell by a sense amplifier. The cell current of the memory cell is used to detect the way information is stored. In addition, in order to supply power to the internal circuit of such a semiconductor memory device, a semiconductor memory device with a built-in step-up power supply circuit for boosting an externally supplied voltage has been developed (for example, Japanese Patent Office, Patent Laid-Open No. 10- Bulletin No. 302492). ...

AI Technical Summary

Problems solved by technology

[0013] However, as described above, the step-up power supply circuit 113 is always operating in a cycle to generate the Vg voltage, so that unnecessary current is consumed.

The step-up power supply circuit 113 consumes a large current in particular, so there is still the problem of unnecessary current consumption.

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