KSZ8051MNL - 10/100 Ethernet MII PHY | Microchip Technology
MPN: KSZ8051MNL ✓ ActiveKSZ8051MNL Overview
An Ethernet physical-layer transceiver is the network-interface circuit that converts digital data from a media-access controller into differential signaling suitable for twisted-pair cabling, then converts received signals back into digital data. Within the broader hierarchy of Ethernet interface components, the KSZ8051MNL belongs to the PHY class, sits below the network interface controller, and ultimately forms part of a complete Ethernet communication system.
The KSZ8051 family is AEC-Q100 standard qualified for automotive applications. The manufacturer describes the KSZ8051 as a highly integrated PHY solution that reduces board cost and simplifies layout through on-chip termination resistors for the differential pairs. It also integrates a low-noise regulator that supplies the 1.2 V core. These features place more of the analog network interface inside the package while reducing the number of external support components needed on the PCB.
The KSZ8051MNL provides the full MII interface, distinguishing it from the KSZ8051RNL version, which uses the Reduced Media Independent Interface. This distinction is important during product selection because RMII and MII are not interchangeable bus arrangements. The MII version is appropriate when the connected controller exposes the required parallel MII signals, clocks, and control lines.
Typical uses include automotive Ethernet gateways, vehicle domain controllers, infotainment platforms, industrial Ethernet equipment, and other 10/100BASE-TX endpoints. In an automotive design, the device can support a wired network connection while the AEC-Q100 qualification provides an automotive-oriented component option. Its integrated 1.2 V regulator and on-chip termination simplify the analog implementation, although the power supply, magnetic-component interface, decoupling, and signal-integrity layout still require careful implementation.
For layout, follow the manufacturer datasheet when assigning the 32 QFN connections and routing the MII and differential Ethernet signals. Keep the 1.2 V bypass capacitor close to its supply pin, route the differential pairs as a controlled-impedance pair, and provide the magnetic-interface network recommended by the datasheet. These practices reduce board-area requirements and help preserve the performance of the integrated PHY.
This product page combines the manufacturer’s device description, package and interface information, documented automotive qualification, source links, and practical implementation guidance. It also distinguishes the MII KSZ8051MNL from RMII and migration-related devices so engineers can identify the appropriate family member without relying on a superficial package-size match.
Drop-in alternatives for KSZ8051MNL — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
No drop-in alternatives available for this product.
Request AlternativesKSZ8051MNL Specifications
| Product Type | 10BASE-T/100BASE-TX Ethernet physical-layer transceiver |
| Manufacturer | Microchip Technology |
| Supported Ethernet Rates | 10 Mbps and 100 Mbps |
| Media Support | 10BASE-T/100BASE-TX |
| Cable Type | CAT-5 unshielded twisted pair |
| Host Interface | Full Media Independent Interface (MII) |
| Channel Count | 1 transceiver |
| Duplex Configuration | Full duplex |
| Supply Architecture | Single supply |
| Internal Core Supply | 1.2 V generated by an integrated low-noise regulator |
| Differential Pair Termination | On-chip termination resistors |
| Automotive Qualification | AEC-Q100 standard qualified |
| Package | 32-pin QFN, 5 mm x 5 mm |
| Mounting Type | Surface mount |
| Lead Finish | Lead free |
KSZ8051MNL 32-pin qfn, 5 mm x 5 mm Pin Configuration Guide
Pin configuration for KSZ8051MNL (32-pin qfn, 5 mm x 5 mm package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for KSZ8051MNL.
Refer to the datasheet for full pin configuration.
Typical Applications
KSZ8051MNL is suitable for 6 applications: Automotive Ethernet Gateway, Vehicle Domain Controller, Automotive Infotainment Ethernet, Industrial Ethernet Endpoint, Network Interface Controller, Wired Automotive Diagnostics.
Automotive Ethernet Gateway
The KSZ8051MNL fits an automotive Ethernet gateway that links a 10/100BASE-TX network to an onboard controller with a full MII interface. Its AEC-Q100 standard qualification, integrated 1.2 V low-noise regulator, and on-chip differential-pair termination reduce the external component count compared with a discrete PHY implementation. The MII connection also makes the device suitable when the selected MAC already exposes the required parallel data and control signals. The main design considerations are the magnetic-interface network, controlled-impedance differential routing, local 1.2 V decoupling, and separation between the Ethernet analog section and switching circuitry.
Recommended
Vehicle Domain Controller
A vehicle domain controller can use the KSZ8051MNL as a dedicated 10/100BASE-TX physical-layer endpoint when the host processor or communications controller provides a full MII. The device supports 10 Mbps and 100 Mbps operation over standard CAT-5 unshielded twisted pair and integrates key analog functions that simplify board implementation. In an automotive design, verify the complete operating-temperature and qualification requirements for the specific vehicle platform. Keep the differential pair geometry controlled, place the magnetic-interface components according to the reference circuit, and decouple the 1.2 V core close to the device as directed by the manufacturer datasheet.
Recommended
Automotive Infotainment Ethernet
The KSZ8051MNL supports a 10/100 Ethernet connection in an infotainment system where a wired network must terminate at an MII-capable controller. Its integrated termination resistors and low-noise 1.2 V regulator reduce board area and simplify the analog support network. The MII interface should be selected only when its required clocks, control lines, and data pins match the host controller because the RMII-based KSZ8051RNL uses a different host-side arrangement. Layout should isolate Ethernet routing from display, audio, and processor power paths while following the manufacturer’s reference schematic and component-placement guidance.
Recommended
Industrial Ethernet Endpoint
The KSZ8051MNL can serve as the 10/100BASE-TX PHY in an industrial Ethernet endpoint when the controller uses the full MII interface. It communicates over standard CAT-5 unshielded twisted pair and provides integrated differential-pair termination and a low-noise 1.2 V core regulator. Its automotive qualification is a useful robustness indicator for harsh installations, but the specific operating-temperature range and product-life requirements must still be checked against the industrial environment. The PCB should use short return paths, controlled-impedance Ethernet traces, and the magnetic network specified by the manufacturer.
Recommended
Network Interface Controller
The KSZ8051MNL can provide the physical layer beneath an Ethernet network interface controller that exposes a full MII interface. This arrangement separates twisted-pair encoding, receive equalization, and cable-side signaling from the MAC’s packet-processing functions. The KSZ8051MNL supports 10BASE-T and 100BASE-TX rates, while the integrated 1.2 V regulator and termination resistors simplify the supporting network. Confirm the MII clocking and signal directions in the datasheet before integrating, and validate that the controller can operate with the PHY’s full-duplex configuration and required media-interface controls.
Recommended
Wired Automotive Diagnostics
The KSZ8051MNL can support a 10/100BASE-TX diagnostic or service-network connection when the vehicle’s communication controller uses a full MII interface. Its 32-pin QFN format supports compact implementation, and the integrated termination and 1.2 V regulator reduce the number of discrete support components around the PHY. For diagnostic use, validate network timing, fault behavior, power-state requirements, and environmental performance against the vehicle specification. The Ethernet pair should remain controlled and isolated from high-current switching paths, while the magnetic interface and bypass network follow the manufacturer’s reference implementation.
Recommended
Recommended Products Summary
Engineering reference data for KSZ8051MNL — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Package | 32-pin QFN, 5 mm x 5 mm |
| Brand | Microchip Technology |
| Ethernet Rates | 10 Mbps and 100 Mbps |
| Media Support | 10BASE-T/100BASE-TX |
| Host Interface | Full Media Independent Interface (MII) |
| Channel Count | 1 transceiver |
| Duplex Configuration | Full duplex |
| Supply Architecture | Single supply |
| Integrated Functions | On-chip differential-pair termination and 1.2 V low-noise regulator |
| Automotive Qualification | AEC-Q100 standard qualified |
Design Notes
Place the 1.2 V bypass network directly beside the relevant supply connection and return it to the device ground with a short, low-impedance path. The manufacturer’s reference schematic places the 1.2 V decoupling components close to the KSZ8051MNL pins. Keep the loop area small and preserve the component values and layout shown in the datasheet, because an unnecessarily long supply connection can couple noise into the integrated PHY and Ethernet receive path.
Route each Ethernet differential pair as a controlled-impedance pair with continuous geometry, matched separation, and minimal stubs. Keep the pair away from switching nodes, high-current inductors, and other sources of common-mode noise. Follow the manufacturer’s component placement and layout guidance around the magnetic-interface network; those parts should connect to the PHY and cable-side network without long loops or unnecessary copper exposure.
Do not treat the KSZ8051MNL as interchangeable with the KSZ8051RNL merely because both use a 32-QFN outline. The MNL version exposes a full MII interface, while the RNL version uses RMII. Likewise, consult the KSZ8051-to-KSZ8081/91 migration material before using a newer family member, because the manufacturer identifies hardware pin differences and changed internal strap values. Verify every footprint, signal, and configuration item before substituting.
Compliance Information
Microchip Technology identifies the KSZ8051 family as AEC-Q100 standard qualified for automotive applications. The KSZ8051MNL is described as lead free. RoHS, REACH, halogen-free, and conflict-minerals status are not established by the product information available for this record.
