LAN9312-NZW
LAN9312-NZW - 2-Port 10/100 Ethernet Switch | Microchip
The Microchip Technology LAN9312-NZW is a two-port 10/100 managed Ethernet switch with a 32-bit non-PCI CPU interface, supplied in a 128-pin XVTQFP package measuring 14 x 14 mm. It combines two Fast Ethernet switch ports, integrated 10BASE-T and 100BASE-TX physical-layer functions, and host-interface logic for embedded equipment requiring controlled integration, network management, and system-cost reduction. The LAN9312 supports full- and half-duplex Ethernet operation and also implements 802.1D and 802.1Q network-management functions.
A managed Ethernet switch is a network-semiconductor device that connects multiple Ethernet ports, controls traffic between them, and provides higher-level functions such as VLAN handling and bridge management. Within the product hierarchy, the LAN9312 is an Ethernet switch, an interface controller, a networking integrated circuit, and a semiconductor designed for embedded systems. Its integrated CPU interface allows a host processor to configure switch registers, monitor status, and manage traffic without requiring a separate external Ethernet controller for basic switched-port operation.
The primary technical features include two 10/100 Ethernet ports, a 32-bit non-PCI CPU interface, 12 configurable general-purpose input/output pins, and support for full- and half-duplex 10BASE-T and 100BASE-TX links. The 12 GPIO pins can operate individually as inputs, push-pull outputs, or open-drain outputs and can generate interrupts with configurable polarity. These resources make the switch useful for products that need Ethernet connectivity alongside status LEDs, reset control, relay control, or other host-monitored signals.
The LAN9312 architecture consolidates switch fabric, Ethernet PHY, network-management registers, and host-interface functions into one integrated device. According to the manufacturer datasheet, the device complies with the IEEE 802.3 Ethernet protocol specification and the 802.1D and 802.1Q network-management protocol specifications. This combination supports standard Fast Ethernet endpoints while allowing embedded software to implement bridging and VLAN behavior. The 128-pin package exposes the required data, control, clock, power, and PHY connections, making careful high-speed and power-layout discipline important in the host board design.
Typical applications include industrial Ethernet gateways, embedded routers, programmable controllers, network-attended test equipment, industrial HMI panels, and compact control systems that need two Fast Ethernet ports. It is particularly relevant where a board must present one Ethernet port to an upstream network and one port to an internal controller or service interface. Because it provides a managed, non-PCI interface, the LAN9312 can also complement higher-speed interface PHYs such as the site-listed DP83867 family when an architecture combines copper Ethernet with additional physical layers.
The main design consideration is integration rather than component substitution. The device requires careful separation of analog and digital supplies, controlled clock and reset behavior, and a PCB layout that minimizes coupling between Ethernet magnetics, PHY circuitry, CPU signals, and switching nodes. The manufacturer placement checklist specifically calls for the Auto-MDIX TX termination pull-up associated with PHY 2 to be placed close to the LAN9312 when Auto MDIX is enabled. A pin-to-pin alternative should not be selected solely from the product family name; its exact package, exposed-pad arrangement, electrical limits, and host-interface behavior must be confirmed against the manufacturer datasheet.
This product page combines the manufacturer product description, the official LAN9312 datasheet, the 128-pin placement checklist, distributor package information, and available cross-reference records. It also provides practical integration guidance, verified pricing evidence where an explicit quantity break exists, and engineering-focused comparison criteria for evaluating a replacement without assuming that a related switch is electrically interchangeable.
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