12V rail isn't shorted, there's only a miniscule increase in power consumption when I turn it on. But the VCCINT rail isn't coming up (according to the supervisor).
Time to dig deeper.
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12V rail isn't shorted, there's only a miniscule increase in power consumption when I turn it on. But the VCCINT rail isn't coming up (according to the supervisor).
Time to dig deeper.
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Andrew Zonenberg
In response to this postVCCINT measures 1.3 ohms to ground. That sounds... not healthy.
Betting it's a solder defect, the paste print there was not very good.
Time to hot air off the DC-DC and see if it clears the short, I guess?
I don't think it's the FPGA, it tested good earlier in the day and I baked it for quite a while before reflow just to make sure.
VCCINT_EN is 18 ohms to ground, while GTY_VTT_EN is much higher (many K ohms). Both use the same DC-DC module.
So I consider that proof of a short under the Murata module for VCCINT.
This explains why the output wasn't even moving on the scope, the module was never turning on.
by Andrew Zonenberg ;
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