Semiconductor memory
AssigneeSharp Kabushiki Kaisha
InventorMasaru Nawaki
Life of this patent
Estimating the term…
Abstract
A semiconductor memory is provided to which external data can be written during a self-refresh. Data thus written can be read out and examined to measure the oscillation frequency of the internal refresh oscillator There is no need to use special equipment such as a frequency counter for testing the oscillation frequency, and the oscillation frequency can be tested after chip sealing.
Claims7
A method for providing self-refresh in a dynamic semiconductor memory having a plurality of memory cells and in which self-refresh is performed during the active period of a refresh control signal, said method comprising a step of:
- refreshing previously stored contents of said memory cells when new input data is not written to said memory cells during self-refresh, and refreshing said memory cells with said new input data in place of said previously stored contents when said new input data is written to said memory cells during self-refresh.
A dynamic semiconductor memory in which self-refresh is performed during the active period of a refresh control signal by using addresses sequentially generated by an internal refresh oscillator and address counter, comprising:
- refresh-write means for enabling input of write data through a data input circuit during said self-refresh, wherein said refresh-write means is activated by an external signal applied during said self-refresh, and wherein said refresh-write means comprise high voltage detection means for detecting when said external signal is raised to a higher than normal voltage state and, upon said detection, providing a write enable signal to said data input circuit.
A dynamic semiconductor memory in which self-refresh is performed during the active period of a refresh control signal by using addresses sequentially generated by an internal refresh oscillator and address counter, comprising:
- refresh-write means for enabling input of write data through a data input circuit during said self-refresh, and
- means for determining the oscillation frequency of said refresh oscillator as a function of data written to said memory during said self-refresh.
A method for providing self-refresh in a dynamic semiconductor memory having a plurality of memory cells and in which self-refresh is performed during the active period of a refresh control signal, said method comprising:
- a step of refreshing previously stored contents of said memory cells when new input data is not written to said memory cells during self-refresh, and refreshing said memory cells with said new input data in place of said previously stored contents when said new input data is written to said memory cells during self-refresh,
- a step of providing self-refresh by using addresses sequentially generated by an internal refresh oscillator and address counter, and
- a step of writing said new input data to said memory cells during a self-refresh of predetermined duration, and thereafter reading the data from said memory in order to determine the frequency of said internal refresh oscillator.
Dependencies are inferred from the claim text.