A memory array is subdivided into many sub-arrays which are separately selectable in groups, with each group containing one or more sub-arrays. The various data bits of a data set are physically spread out and mapped into a large number of associated sub-array groups. All the associated sub-array groups are preferably selected during a read cycle to simultaneously read the various bits of the data set, but when writing the data set, a smaller number of sub-array groups are activated during each of several write cycles to simultaneously write only a portion of the data set. Consequently, the read bandwidth remains high and is driven by the number of bits simultaneously read, but the write power is reduced since during each write cycle fewer bits are written. Such a memory array is particularly advantageous with passive element memory cells, such as those having antifuses.