USB Hosts Hubs Transceivers

[ErDE_3356256]

Hello,

We use the HX3 Hub P/N CYUSB3326-88LTXCT, associated with a 2-kbit EEPROM for custom configuration settings, and we need a clarification about a conflict between two documents: the HX3’s data sheet (Document Number: 001-73643 Rev. *T) and application note AN91378 (Document No. 001-91378 Rev. *B).

Indeed, the first document (page 22) said about the DS4_LED_SS pin: “If LED is not used, this pin must be pulled HIGH using a 10 kΩ to VDD_IO”. However, the second document (page 29) said about the BOM Reduction to CY4613 that a number of resistors including the pull-up (R50) on DS4_LED_SS pin “can be removed only if pin-strap configuration is not used. If you are using external EEPROM firmware for configuration, then the pin-strap option has no effect”.

Therefore, since we have a small EEPROM for our configuration settings and we do not use an LED on DS4_LED_SS pin, is it possible to leave this pin floating or do we have to pull it HIGH to VDD_IO?

Best Regards

[Sananya_14 · Accepted solution]

Hello,

Yes you can leave the pin floating. Since you are not connecting a LED, it is recommended to pull it high as mentioned in the datasheet. However the pin will only be sampled if you enable Pin-Strap boot mode and since you are using I2C master boot mode, you can leave it floating.

Best Regards,

Sananya

[ErDE_3356256]

Hi Sananya,

Thank you for your reply. Now it's clear.

Best Regards,

Eric.