Dear All,
The TPS75003 is a triple voltage regulator designed for the Spartan-3 & Spartan-3E series. It's got some quite specific component requirements. Unfortunately, the datasheets and appnotes list parts that aren't that easy to source in the UK.
I've put together a list of parts available from Farnell (UK) that seem to work well.
The list and a PCB design are available here:
Hopefully this will save time for anyone else who plans to use the device.
Andy
-- Dr. Andrew Greensted Department of Electronics Bio-Inspired Engineering University of York, YO10 5DD, UK Tel: +44(0)1904 432828 Mailto: ajg112@ohm.york.ac.uk Fax: +44(0)1904 432335 Web: http://www.bioinspired.com/users/ajg112
Thanks a lot for this. I've been struggling with a TPS75003 design for a few days, trying to find parts that would be easy to get (inductors are the major issue).
Have you tested the design ? Application notes and reference design I found were all able to supply 2.5A-3.0A @ 1.2V. I'm a bit concerned about this, as typical FPGA consumption for the Spartan3E-500 FPGA I plan to use is much lower than that. Have you measured ripple on 1.2V at low load and no load ? I'm also concerned about load change (such as when the FPGA is configured/unconfigured), have you made any measurement there ?
Best regards,
Laurent Pinchart
Hi Laurent,
Yep, it does work. I've built up the board, and tested it. Currently it's powering four Spartan-3Es, the total current drawn (for 3.3V, 2.5V & 1.2V) is only about 150mA, but each FPGA is doing _very_ little.
I've not had a chance to do any testing of ripple etc... or try different load conditions. When I do, I'll add the results to the web page.
Andy
-- Dr. Andrew Greensted Department of Electronics Bio-Inspired Engineering University of York, YO10 5DD, UK Tel: +44(0)1904 432828 Mailto: ajg112@ohm.york.ac.uk Fax: +44(0)1904 432335 Web: http://www.bioinspired.com/users/ajg112
I've just done a quick measure of the ripple:
3.3V is about 90mV 1.2V is about 20mV(The 2.5V is the LDO, so ripple is low, about 10 mV, general noise really)
Again, this is under low load conditions.
Andy
-- Dr. Andrew Greensted Department of Electronics Bio-Inspired Engineering University of York, YO10 5DD, UK Tel: +44(0)1904 432828 Mailto: ajg112@ohm.york.ac.uk Fax: +44(0)1904 432335 Web: http://www.bioinspired.com/users/ajg112
Andrew
You can get away with quite a lot of component variations. We don't use this regulator on any of our development boards but do use it on some customer designs and it's ok. It does suffer from not having a particularly high switching frequency giving big magnetics and the external mosfets are a bit of pain compared to some the Linear Technology parts we now use in preference. The 2/3A ratings you are unlikely to need for most Spartan-3 based designs unless you have a lot of ancilliary bits and often the inductor current ratings use can as a result be smaller often than the example circuits.
John Adair Enterpo> Dear All,
here:
Dear Group, For anyone starting out designing switched mode power supplies, you could do worse than read Linear Tech's appnote, AN19, by Carl Nelson. Although it's written for the ancient LT1070, it is an excellent introduction to the many types of switching regulator topologies. There's also an inspired section called 'Troubleshooting Hints'. My favourites are numbers 5 and 12. See below. HTH., Syms.
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