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There's a phrase in software development "eat your own dogfood". In fact, there's even an ugly verb "dogfooding". This means using your own software for real. If, say, you are developing a source-code management system (although why would you, Linus Torvalds already did that for you with git) then you use your own software to manage your source code. Cadence has a hardware business as well as EDA tools: the Palladium Z1 and Protium X1 platforms. As far as I know, we eat our own dogfood and only use our own tools to design these boxes (except for FPGA P&R since that comes from the vendor).
At the recent CadenceLIVE, Isaac Lee and Karthick Gopalakrishnan presented System-Level Thermal Analysis of Protium Platform Using Celsius Thermal Solver. They started with a guide to Celsius, but I'm going to skip that since I've covered it in:
Protium X1 is a modern, blade-based hardware and debug software for early firmware and software development, high-performance hardware regression, and full-system validation. It goes into an enterprise rack and is intended to be installed in the data center. I've written about Protium before, too, in:
Inside the chassis, there are "blades", which have an enclosure and contain three boards. Depending on how big a system you purchase, you get some number of these. Each blade is a 17.5in x 33.5in x 5.2in air-cooled chassis that dissipates 900W (not the actual number, but gives you an idea we're not talking about 25W nor 10KW). Each blade contains three boards, one with 2 FPGAs, one with 4 FPGAs, and an interface board. If it's not obvious, now you know why each blade can be used by up to six users (if the designs are small enough to fit in a single FPGA). The main source of heat are the FPGAs, of course, so they have big heatsinks.
The goal of the analysis described in the presentation was to predict component operating temperatures of the major heat-dissipating components of the blade from a steady-state thermal analysis, and optimize the design if required. The diagram above shows how the blades go in Protium. There are three different kinds of boards: one with two FPGAs for prototyping, one with four FPGAs, and an interface board. There are heatsinks on the FPGAs and two fans in the center of the enclosure that draw air in from the front and force it out the rear.
The analysis was done by:
The analysis by the Celsius Thermal Solver took two hours to simulate, based on 12 million elements. There are only a few dozen components but we had a very detailed model of the heatsinks. That two hours is both for meshing and solving. The meshing is entirely automatic, with no manual guidance required.
The final step was to compare the results from the analysis to the operational limits. The worst was the interface board that had three components with negative margin, the worst being -26ºC (negative is bad), and two more borderline at -1ºC.
A tradeoff study was done as to how to make the temperature within its specification.
Two things were considered:
Adding the air baffle got to -5ºC (negative is bad remember)
Adding the third fan meant all the components met their specs (see the pictures above)
So in summary:
A few additional points came out of the Q&A:
Radiation? Yes, the Celsius Thermal Solver can handle it (but didn't do it in this study)
Transient? This was steady-state analysis, but the Celsius Thermal Solver can do transient analysis
Bult-in models? We have some, like material libraries. We don't have fan models but support them.
Learn more about the Celsius Thermal Solver.
Learn more about the Protium X1 Enterprise Prototyping Platform.
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