Default Configuration for BYTE Pin in NOR Flash Memory - KBA224429

Version 5

    Author: PradiptaB_11         Version: **

     

    Translation - Japanese: NOR Flash memoryのBYTE# pinのデフォルト状態について – KBA224429 - Community Translated (JA)

     

    Question:

    What is the default state of the BYTE# pin? Is there an internal pull up or pull down on the pin that will set it to a known configuration if the pin is left floating?

     

    Answer:

    Cypress’ NOR Flash memories such as S29GL-P, S29JL-J, S29GL-N, S29GL064S, S29AL-J, S29AS-J do not have any internal pull up or pull down for the BYTE# Pin. The BYTE# pin controls whether the device data I/O pins DQ15–DQ0 operate in the byte or word configuration. If the BYTE# pin is set at logic 1, the device is in word configuration and pins DQ15–DQ0 are active and controlled by CE# and OE#. If the BYTE# pin is set at logic 0, the device is in byte configuration, and only data I/O pins DQ0–DQ7 are active and controlled by CE# and OE#. The data I/O pins DQ8–DQ14 are tri-stated, and the DQ15 pin is used as an input for the LSB (A-1) address function.  Hence the BYTE# pin needs to be set to either of the following mode operation and cannot be left floating:

    • VIL or VIH mode
    • x8 or x16 mode

    Only the GL-T series has an internal pull up and can be left open when used in x16 mode.