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VBUS, GND and SHIELD schematics
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VBUS, GND and SHIELD schematics

Nazila posted on 22 Nov 2011 6:09 PM PST
Top Contributor
55 Forum Posts

Hi,

The VBUS connection is a bit confusing. Specifically after reading the application note: AN1168 (Please compare this application note with the schematics). 

How should I connect the VBUS to the CYUSB3014 if I only want to use the CYUSB3014 as a cell-power device only (No OTG application). Do I need to use 39K or 62K resistors (AN1168) along with the BLM21PG221SN1D (inductor)? I would appreciate it if you could also specify the whole path from the VBUS pin on the USB connector to the VBUS pin on the CYUSB3014.

Thanks,

Nazila

Re: VBUS, GND and SHIELD schematics

aasi posted on 23 Nov 2011 10:38 PM PST
Cypress Employee
1073 Forum Posts

The datasheet has a section which explains the extra circuitry needed and the reason. Please check if this is the case, if so please use the DVK schematic as reference.

If you look at AN1168 it doesn't recommend value for the resistor on VBUS line i.e. the figure is just for demonstration, the value and circuit to be used will be based on your requirement.

If this is not clear please add more information on your design (self-power/bus-power, end application, charging supported etc) so that we can understand the design better

Regards,

Anand

Re: VBUS, GND and SHIELD schematics

sodafarl posted on 28 Nov 2011 01:04 AM PST
Top Contributor
128 Forum Posts

Hi,

Dose the FX3 need a connection to VBUS before it can operate. The data sheet page seems to suggest  that VBUS  or VBATT powers the FX3 USB transceivers. So if VBUS is not present would VBATT be okay to power the FX3 USB transceivers.

Sodafarl

Re: VBUS, GND and SHIELD schematics

aasi posted on 29 Nov 2011 01:24 AM PST
Cypress Employee
1073 Forum Posts

Please look at http://www.cypress.com/?app=forum&id=167&rID=55972

Regards,

Anand

Re: VBUS, GND and SHIELD schematics

sodafarl posted on 29 Nov 2011 04:26 AM PST
Top Contributor
128 Forum Posts

Hi,

Thansk for your answer Anand. What instructions are needed in the firmware to cause the FX3 to use VBATT instead of VBUS.

Sodfarl

Re: VBUS, GND and SHIELD schematics

aasi posted on 30 Nov 2011 09:56 PM PST
Cypress Employee
1073 Forum Posts

Please look at CyU3PUsbVBattEnable in FX3 API guide.

Regards,

Anand



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