C5515 USB LDOI minimum voltage

Christos Nikolaou12204

Hi,

We have received a first batch of our own designed boards with C5515 and we perform some tests and see any issues.

I would like to know if I can feed as low as 1.3V to the USB LDOI input (F13) and the chip's USB controller still perform ok.

Christos

over 15 years ago

0 Steve Tsang over 15 years ago

TI__Mastermind 23785 points

Hello Christos,

It is 1.8V to 3.6V. It is on page 34 of System User's Guide SPRUFX5A.

Steve

0 Christos Nikolaou12204 over 15 years ago in reply to Steve Tsang

Expert 1790 points

Hi Steve,

Yeah I know..

Yet on the first batch that I received due to an error it has 1.3V but it does work !! :-)

I admit it is a bit clanky and It has though lower speed, about 13MB/sec compared to 24MB/sec.

Just wanted to share this !!

Christos

0 Steve Tsang over 15 years ago in reply to Christos Nikolaou12204

TI__Mastermind 23785 points

OK. Christos.

I am actually trying to reach the desiger to ask the "what if" 1.3V question. i will let you know once I got it. I understand the feeling when you just get the design back.

Steve

0 Christos Nikolaou12204 over 15 years ago in reply to Steve Tsang

Expert 1790 points

The strange thing is that it passes (with a lower though speed) the plain CSL2.10 USB tests.

It fails when I put a USB endpoint in test condition (IN NAK).

Its definitively not working ok in that particular case but it is quite interesting to see the whole CPU working with 1.3 V in some of its LDOI and yet passing the CSL tests.

It is a limited pilot-run just to see any issues so no harm done and since we used the TPS76601 we'll just do a bit of rework and change the reference resistors and see how it goes.

0 Peter Chung over 15 years ago in reply to Christos Nikolaou12204

TI__Expert 8065 points

Christos,

First of all, please help us understand why you use 1.3V to the LDOI pins? Do you have a specific reason?

With 1.3V to LDOI pins, some devices may work in certain condition but we can't guarantee that all device will work with 1.3V LDOI input. Please supply suggested voltage to LDOI pins for proper operation. 1.3V to LDOI is outside of design spec. I think you understand I am trying to point out. Please follow the suggested voltage range.

Regards,

Peter Chung

0 Christos Nikolaou12204 over 15 years ago in reply to Peter Chung

Expert 1790 points

Hi Peter,

There is no issue, if you see my posts I say that because of an error we've given 1.3v to USB LDOI and I was quite surprised to see it working even at that point and passing the CSL tests (although failing some proprietary code).

As I said I just wanted to share this because it was a nice surprise.

Christos

0 Steve Tsang over 15 years ago in reply to Christos Nikolaou12204

TI__Mastermind 23785 points

Hello Christos,

Actually it is not a surprise if you are familair with TI. TI has been providing quality and innovative products for more than 75 years and keep on strong. We are also committed to help our customers to solve their problems.

I have talked to the designer, and just like Peter stated, we cannot guarantee every devices function properly when operate outside of specified operating conditions. And I can see that you are aware of it and plan is already in place.

Thanks for sharing your finding with us.

Regards,

Steve

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C5515 USB LDOI minimum voltage