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Apparatus and method for self-refreshing dynamic random access memory cells

  • US 8,045,365 B2
  • Filed: 03/02/2010
  • Issued: 10/25/2011
  • Est. Priority Date: 12/29/2005
  • Status: Expired due to Fees
First Claim
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1. A method for low power refreshing a dynamic random access memory (DRAM) having cells arranged in rows and columns, comprising:

  • refreshing the cells in a one cell-per-bit mode at a first frequency during a normal mode of operation where the cells are read and written in the one cell-per-bit mode;

    entering a self-refresh mode for reducing refresh power consumption;

    generating refresh addresses including a starting refresh address for selecting a first row of cells to be refreshed, by an address counter;

    executing a dummy refresh cycle in response to a comparison between the starting address and a predetermined address;

    refreshing the cells in a two cell-per-bit mode at a second frequency lower than the first frequency during the self-refresh mode in response to the refresh addresses and beginning at the starting refresh address; and

    ,exiting the self-refresh mode to resume the normal mode of operation.

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