2 Replies Latest reply on Jan 20, 2019 4:11 PM by user_3968496

    S25FL512S Flash IO voltage levels during READ with zynq 7010

    user_3968496

      I am verifying the interface between the qspi flash, S25FL512S, to zynq 7010 on HW level.

      zynq 7010 PS is VCCO_MIO is 1.8V

      The VCC_IO of qspi flash is 1.8V

      I am measuring the voltages of the nodes for read and write to the flash.

      nCS and SCK are measured to have a high voltage of about 1.8V for both read and write, which is correct.

      for IO(3-0), high voltage of about 1.8V is also measured for write operation. No problem here as well

       

      But for read operation, a high voltage if about 2.6V is measured on IO(3-0).

      2.6V is higher than the absolute maximum DC rating of PS_MIO of VCCO_MIO +0.55V = 1.8+0.55 = 2.35V

       

      On the Pg 25 datasheet of S25FL512S QSPI Flash Datasheet: during voltage transitions, inputs or I/Os may overshoot VSS to –2.0V or overshoot to VIO +2.0V, for periods up to 20 ns. - I am not sure if there is any overshoot in my measurement.

       

      QUESTION:

      What is the cause of the high voltage of IO(3-0) during the read operation?

      How can I reduce this voltage?

      Is this voltage is acceptable?

       

      thanks

      SW