I am designing a project using the C5515. I do not plan to use the USB module in my application. Do I need to connect any of the USB power pins to either power or GND?
From the c5515 datasheet, if you are not using the USB subsystem, then the Core, PHY and I/O supplies can be powered down.
Datasheet: http://www.ti.com/lit/ds/sprs645e/sprs645e.pdf (pg.78)
The LDOI pins must always be powered on. The USB_VDDxxx pins should be connected to ground if not in use (pg. 45 of datasheet).
If a post provides a solution to your question, please 'verify answer'!
Thanks Keegan. Saved me hours of searching.
Keegan (or anyone else who can answer).
Would it hurt to leave one of the 3 LDOI pins (i.e. F13) floating? We inadvertently tied it to ground and can cut the trace to the BGA pin F13, but can't reconnect F13 to another pin (no way to add a trace that small). Are F13, F14, and B12 all tied together in the die?
Wish I could give you some good news, but I cannot recommend floating those pins as the pins source not only the LDOS but many of the on-chip peripherals and PLLs through those LDOs. My guess is that these input pins are not tied together in the die, but I could be wrong there.
Thanks for the feedback, but I really have no choice but to try. To clarify, per the initial question in the thread, I have grounded all of the USB peripheral VDD pins since I do not plan to use the USB section. So, hopefully the USB_VDD LDOI pin (which appears to be tied to the other LDOI inputs since grounding it shorts the others to ground) is simply another current source for the USB section and is tied to the other LDIO pins inside the chip.
For those of you who have made similar design errors on a BGA-based device like the C5515, I had the board re-worked by a group in the Chicago area by the name of BEST (Business Electronics Soldering Technology - http://www.solder.net/). They removed the C5515, cut the trace that was shorting the USB_VDD_LDOI pin to ground, and added a trace to the correct adjacent pad, and installed a new C5515. THE BOARD NOW WORKS FLAWLESSLY! The process was fairly painless (other than my high anxiety) and was turned around in a week.
I just wanted to let everyone know that a BGA layout error is not necessarily a catastrophic event....:)
Fanstastic news Mike! Thanks for providing your solution!
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.