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@azonenberg@ioc.exchange
2025-06-21 08:06:31

Doing a more extensive SI/PI workup on the switch line card in preparation for a) a blog update on the switch project and b) getting all my I's dotted and T's crossed before spending a lot of money stuffing three more boards and ordering the logic board.
Here's the 2.5V rail, putting out a bit over 2A at 2.5V. Ripple is dominated by ~300 kHz switching noise plus some harmonics of the 125 MHz PHY symbol rate (which makes sense this rail is driving the PHY PAM5 transceivers a…

ngscopeclient screenshot showing FFT and time domain views of a nominally 2.5V power rail that's actually closer to 2.48. There's some very slight switching spikes and the FFT shows harmonics of the PHY clock but they're at < -70 dBm