What this Ethernet PHY does in the assembly
The KSZ8091RNDIA-TR is a single-port Ethernet transceiver (PHY) handling the physical-layer encoding and decoding for 10/100BASE-TX signals. It implements full-duplex operation, meaning the transmit and receive paths run simultaneously on the same twisted pair, doubling the effective data rate over half-duplex links. With one driver and one receiver, it connects a single MAC (Media Access Controller) to the Ethernet cable — typical for an embedded node, industrial sensor, or gateway where only one Ethernet port is needed.
Supply voltage flexibility and temperature range
The PHY accepts a wide supply range of 1.8V, 2.5V, or 3.3V, allowing it to interface directly with low-voltage SoCs (1.8V) or legacy 3.3V MACs without level shifters. This reduces BOM count and simplifies PCB routing. Rated for -40°C to 85°C, it suits industrial environments such as factory-floor Ethernet switches, outdoor surveillance cameras, and automotive cabin telematics — not full MIL-spec, but the common industrial temperature grade.
Package and mounting considerations
Housed in a 24-VFQFN exposed pad (4x4 mm), the package requires a thermal pad on the PCB for heat dissipation. The exposed pad must be soldered to a ground plane to keep junction temperature within limits during continuous 100BASE-TX operation.
Lifecycle and sourcing posture
Microchip lists the KSZ8091RNDIA-TR as Active, meaning no end-of-life notification has been issued. For ongoing builds, this part carries no forced redesign risk. ROHS3 compliant. Sourced per RFQ — confirm current pricing and lead time at quote. No stock-holding claim; availability confirmed at order time.