What this 1:4 clock buffer is and where it fits
The Renesas 621SCMGI8 is a single-ended clock buffer that takes one clock input and drives four copies at up to 200 MHz. It is designed for general-purpose clock distribution on boards that need to fan out a reference clock to multiple loads.
200 MHz ceiling and single-ended I/O — what they mean for the design
The 200 MHz maximum frequency covers most SPI, I2S, and parallel-bus clock trees, but it is not a differential buffer (No/No on both input and output). That means it cannot cleanly propagate a high-speed differential clock like LVPECL or LVDS — for those, look at a dedicated fanout buffer such as the 8SLVP2108. The single-ended input also means the device is sensitive to noise on the clock trace; keep the trace short and run a solid ground plane underneath. The 1:4 ratio is fixed — no configurability — so if you need a 1:2 or 1:8 fanout, this part does not stretch.
Supply and temperature — industrial range, wide voltage
The 1.71 V to 3.465 V supply covers the three common digital rail voltages: 1.8 V, 2.5 V, and 3.3 V. At 1.8 V the margin is tight — the minimum is 1.71 V, so a 1.8 V rail with a 5% tolerance (1.71 V) just meets the spec. If your rail sags under load, consider a 2.5 V or 3.3 V supply for headroom. The -40°C to 105°C range is full industrial; the part can sit in an unventilated enclosure or near a warm processor without derating.
Package and footprint — 8-VFQFN (2x2 mm)
The 621SCMGI8 comes in an 8-VFQFN package with a 2 mm x 2 mm body (supplier device package 8-VFQFN). It is a surface-mount, leadless package with an exposed pad — the pad should be soldered to a ground plane for thermal and electrical continuity.
Lifecycle and sourcing reality
The 621SCMGI8 is listed as Active on the manufacturer's status — no last-time-buy or end-of-life notice. It is RoHS3 compliant. For a BOM line, this means no imminent obsolescence risk and no need to qualify a substitute for production. The closest functional peer is the 5PB1104CMGK/W from the same family: same 1:4 ratio, same 200 MHz ceiling, same LVCMOS output type, same supply and temperature range. The difference is the package — the 5PB1104 comes in a different 8-pin package — so verify footprint compatibility before swapping.