Hello everyone,
i am using a W25Q128FV to store data. I read about a Write-Protect delay after Startup in the Datasheet. This takes over 40 seconds for me. Is it supposed to take that long?
Thanks in advance
Can you enlighten us about what the data sheet said about that? A link to the data sheet would also be convenient.
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Sure, i am sorry:
Upon power-up or at power-down, the W25Q128JV will maintain a reset condition while VCC is below the
threshold value of VWI, (See Power-up Timing and Voltage Levels and Figure 43). While reset, all
operations are disabled and no instructions are recognized. During power-up and after the VCC voltage
exceeds VWI, all program and erase related instructions are further disabled for a time delay of tPUW. This
includes the Write Enable, Page Program, Sector Erase, Block Erase, Chip Erase and the Write Status
Register instructions. Note that the chip select pin (/CS) must track the VCC supply level at power-up until
the VCC-min level and tVSL time delay is reached, and it must also track the VCC supply level at powerdown to prevent adverse command sequence. If needed a pull-up resister on /CS can be used to
accomplish this
Well that seems straightforward. What is the published value of "tPUW"?
How do you know?
tPUW is 5 ms.
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The busy bit of the Status register is high for this period. I measured the time the busy flag is on. It also says min 5ms in the Dataseet
Better post your schematic.
Data sheet says,
"A Write Enable instruction must be issued before a Page Program, Sector
Erase, Block Erase, Chip Erase or Write Status Register instruction will be accepted."
Did you?
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Yeah, i can write after waiting for ages. It's just that this flag is high for ages. Also if there's data on the chip i don't have to wait at all. It only happens when the chip was erased befor power down.
Schematic:
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