Page mode writing method for an EEPROM and corresponding circuitry

摘要

The method for writing in page mode, where page corresponds to a column of planar memory store in a memory circuit of EEPROM type, comprises (i) an initialization phase for writing the page selection information into a latch or bistable circuit of memory store associated with a column of planar read-only memory, and writing of the page data in a temporary memory (MT) store; (ii) a writing phase for the selection of memory rows (Row0,..., Rowp) as a function of contents of temporary memory store. The method also comprises the utilization of a latch per column of planar memory for the storage of page selection information, and a control logic circuit for the provision of row selection signals as a function of contents of temporary memory store in the writing phase. The planar memory of an array type contains columns (Col0,...,Colm) and rows (WI0,...,WIp) of word memories, where each word memory contains a set of memory cells (C0,...,C7), each associated with one of bit lines (B0,...,B7),a row decoder (DECX) and a column decoder (DECY) delivering signals for the selection of rows (Row0,...,Rowp) and columns (Selcol0,....,Selcolm) respectively, for the application of an appropriate voltage level for the access in reading and writing. The writing phase comprises an erase phase and a programming phase, and the programming is effected by use of bit lines of the selected column. Each word in temporary memory (MT) comprises information bits (DATABIT0,..., DATABIT7) corresponding to the data to be written, and a position bit (POSBIT) of word in page. In the erase phase, the page selection information is stored in one of the latches, allowing the application of higher voltage to the selected column. The architecture of read-only memory in an integrated circuit is that of an array type with columns and rows as described. Each latch in writing operation is controlled by a corresponding selection signal (Selcol0,...Selcolm). The temporary memory (MT) comprises p+1 elementary memory stores (MOT0,...,MOTp), each containing latches with input and output nodes (Q,/Q) for 1+8 bits, the position bit and the data bits. The memory architecture also comprises means for the provision of a clock signal and a higher voltage clock signal for sequencing the programming of each bit line, which are prepared to the control logic circuit and to a higher voltage switching circuit.