7 Replies Latest reply on Apr 21, 2020 7:35 AM by SudheeshK_26

    Is Pull-up of DQ /RWDS required?

    KeTa_1341526

      Hello,

       

      [Question]

      Is Pull-up of DQ / RWDS required?

       

      [Background]

      In P.25 [7. Interface States] of the following materials, it is stated that DQ / RWDS is in High-Z state during Cold / Warm Reset or Standby.

      https://www.cypress.com/file/213356/download

      I think this requires the Master MCU to place the bidirectional pins in the High-Z state.

      In other words, since Hyper Flash and MCU are in High-Z state with each other, I think it is necessary to prevent latch-up due to shoot-through current.

      In order to prevent this, it is the recognition that pull-up must be attached to the signal line.

       

      However, when I looked at the schematic of the reference board (IMXRT1050-EVK) below, there was no external pullup.

      https://www.nxp.com/docs/en/nxp/application-notes/AN12239.pdf

       

      Is Pull-up unnecessary?

       

      Best regards,

      Takahashi