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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.
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?