Cypress manual CY7C145, CY7C144

Notes

21.The internal write time of the memory is defined by the overlap of CE or SEM LOW and R/W LOW. Both signals must be LOW to initiate a write, and either signal can terminate a write by going HIGH. The data input set-up and hold timing should be referenced to the rising edge of the signal that terminates the write.

22.If OE is LOW during a R/W controlled write cycle, the write pulse width must be the larger of tPWE or (tHZWE + tSD) to allow the I/O drivers to turn off and data to be placed on the bus for the required tSD. If OE is HIGH during a R/W controlled write cycle (as in this example), this requirement does not apply and the write pulse can be as short as the specified tPWE.

23.R/W must be HIGH during all address transitions.

24.Data I/O pins enter high impedance when OE is held LOW during write.

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