TMS320C5545: What to do with the USB pins if USB module is not required in the custom board

sathish v

Part Number: TMS320C5545

Hi,

We are using C5545 DSP in our project to process a voice signal. We are creating a custom board out of C5545 booster pack. We don't require USB interface in our project. So If we just don't connect the usb pins (ex: USB_MXI, USB_MXO, USB_VBUS, etc) will be enough or do we have to Ground all these unused pins?

Regards,

Sathish V

over 6 years ago

0 Cvetolin Shulev-XID over 6 years ago

TI__Guru 65405 points

Hi Sathish,

You can leave unused USB pins floating (not connected).

BR
Tsvetolin Shulev

0 Tom Makovicka over 6 years ago in reply to Cvetolin Shulev-XID

Intellectual 400 points

For the C5505, C5515, and C5535, this ( processors.wiki.ti.com/.../35_Schematic_Checklist ) websites states that

Unused Power Rails
If USB is not used

Terminate USB pins to permanently disable USB:
USB_MXO must be left unconnected
USB_LDOO must be left floating (can be disabled in software - LDOCNTL register [7004h])
USB_R1 signal must be connected via a 10kOhm resistor to ground
Short the following USB pins directly to ground:
USB_MXI
USB_VDDOSC
USB_VSSOSC
USB_VBUS
USB_DP
USB_DM
USB_VSSREF
USB_VDDA3P3
USB_VDDA1P3
USB_VDD1P3
USB_VDDPLL
USB_VSSPLL
USB_VSS1P3
USB_VSSA3P3

Is this NOT correct for the C5545?

Tom

0 Tom Makovicka over 6 years ago in reply to Cvetolin Shulev-XID

Intellectual 400 points

This ( processors.wiki.ti.com/.../35_Schematic_Checklist ) websites states the following on what to do with unused USB pins for the C5505, C5515, and C5535. Is this not true for the C5545?

Tom

Unused Power Rails
If USB is not used

Terminate USB pins to permanently disable USB:
USB_MXO must be left unconnected
USB_LDOO must be left floating (can be disabled in software - LDOCNTL register [7004h])
USB_R1 signal must be connected via a 10kOhm resistor to ground
Short the following USB pins directly to ground:
USB_MXI
USB_VDDOSC
USB_VSSOSC
USB_VBUS
USB_DP
USB_DM
USB_VSSREF
USB_VDDA3P3
USB_VDDA1P3
USB_VDD1P3
USB_VDDPLL
USB_VSSPLL
USB_VSS1P3
USB_VSSA3P3

0 Mark M over 6 years ago in reply to Tom Makovicka

TI__Mastermind 29520 points

Hi Tom,

Guidance for terminating unused USB pins on C5545 is the same for C5505/15/35. That Schematic Checklist you found is accurate.

I believe the goal for grounding all those supplies and pins is power savings.

The C5505 eZdsp is an EVM you can refer to where USB not used. It has the respective supplies and pins GNDed.

http://www.ti.com/tool/TMDX5505EZDSP

http://support.spectrumdigital.com/boards/usbstk5505/revd/

Regards,
Mark

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TMS320C5545: What to do with the USB pins if USB module is not required in the custom board