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CY7C65640 and blank 25LC040 | Cypress Semiconductor

CY7C65640 and blank 25LC040

Summary: 2 Replies, Latest post by VAVC on 13 Nov 2013 01:26 AM PST
Verified Answers: 0
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AOrecArcher's picture
1 post


In my design I have CY7C65640-LTXC and EEPROM 25LC040-ISN. Is it a MUST to load EEPROM with at least default configuration 0xD0 Load, or will the USB hub run correctly when EEPROM blank? How would I go on about programming this EEPROM?

On power up sometimes (1 in 15 time) CY7C65640-LTXC is stuck and the hub is not operating properly (it does not recover after chip reset, only on power up), could this be because EEPROM is blank?

Thank you.




prji's picture
Cypress Employee
473 posts


You need to use a separate EEPROM programmer. Please inquire the vendor where you purchased the EEPROM from for further information on how to program these parts.

Were you able to reproduce the issue without EEPROM?



VAVC's picture
Cypress Employee
506 posts


For tetra HUB CY7C65640, if no EEPROM is used or the connected EEPROM is not programmed, then HUB enumerates with default descriptors. For details on default descriptors refer page no. 9 in the datasheet of CY7C65640A.

download the datasheet from the following link




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