| abstract |
(57) [Summary] [Objective] By installing a temperature sensing device inside a memory element and dividing the sensed temperature region into a plurality of regions, the temperature change of the memory cell array can be sensed more accurately and self refresh operation can be performed. It is an object of the present invention to provide a self-refresh control circuit of a memory cell array in which a cycle can be adjusted and one timer generates a plurality of self-refresh operation cycles to reduce a chip area. [Structure] In a control circuit of a memory cell array composed of a plurality of memory cells and their address buffers and decoders, a reference voltage is generated using a resistor made of a substance whose resistance value is almost constant regardless of temperature change. A variable voltage is generated by using a resistor made of a substance whose resistance value greatly changes due to temperature change. Then, the temperature inside the memory cell is sensed by comparing the reference voltage with the variable voltage, and the self-refresh cycle is appropriately set according to the sensed temperature. |