Obsolete but findable — the sourcing reality for DSC6121HI2A-0090T
Microchip officially lists the DSC6121HI2A-0090T as Obsolete. No successor part number is provided in the record, so the only path to this exact order code is through surplus or broker inventory — not a last-time-buy from the factory.
Dual-frequency output — what the 6.1298 MHz and 6.1679 MHz mean
This XO (Standard) generates two independent CMOS clock outputs: 6.1298 MHz and 6.1679 MHz. That pair is unusual — it is not a common base frequency like 25 MHz or 50 MHz — which suggests it was designed for a specific chipset or SoC that requires two slightly offset reference clocks, possibly for a SerDes or a dual-core timing domain.
Package and temperature — board-fit and deployment
That is a tiny land-grid array — the footprint is smaller than a 0805 resistor. Replacing it on a board requires a hot-air station with a fine nozzle; the pad pitch is not specified but at this body size it is likely 0.50 mm or tighter. No exposed thermal pad to worry about, but the solder paste volume needs to be precise to avoid bridging.