LAN8770M-I/PRA - 100BASE-T1 Automotive Ethernet PHY | Microchip
MPN: LAN8770M-I-PRA ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.12 | $4.12 |
| 10 | $3.95 | $39.50 |
| 100 | $3.7 | $370.00 |
| 500 | $3.48 | $1,740.00 |
| 1,000 | $3.25 | $3,250.00 |
LAN8770M-I-PRA Overview
An Ethernet PHY transceiver is the physical-layer device in the OSI model that converts digital MAC-layer frames into analog signals suitable for transmission over copper media. Within the network hierarchy - Ethernet MAC, PHY transceiver, magnetics/connectors, cable - the PHY sits directly between the MAC and the physical medium, handling encoding, equalization, echo cancellation, and link management. In the 100BASE-T1 (formerly automotive BroadR-Reach) category, the PHY enables full-duplex 100 Mbit/s communication over a single unshielded twisted pair, dramatically reducing cabling weight and cost compared with 100BASE-TX.
Key features of the LAN8770M include MAC interface support for standard MII and RMII protocols, an integrated SMI (Serial Management Interface) for rapid register access and configuration, and an optional 50 MHz reference clock output for RMII applications. The M-variant adds Reverse MII mode, which allows two PHYs to be connected back-to-back - useful in media converter and test architectures. Unlike the LAN8770R variant, this device does not include an RGMII interface, keeping cost and pin count low.
Technically, the device integrates the analog front end, ADC/DAC signal path, and DSP equalization required for single-pair operation on one 1.1 V core supply with 3.3 V I/O, supporting -40C to +85C operation for demanding vehicular and industrial environments.
Typical applications include automotive ECU-to-ECU networking, ADAS camera and sensor links, 100BASE-TX to 100BASE-T1 media conversion (as demonstrated on Microchip's EVB-LAN8770M_MC evaluation board), and industrial single-pair Ethernet backbones.
Design consideration: 100BASE-T1 requires a single differential pair with common-mode termination and isolation network per the reference design; follow Microchip's layout guidance for the exposed pad thermal/electrical ground connection.
This page synthesizes distributor pricing, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for LAN8770M-I-PRA — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LAN8770R-I/PRA
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LAN8770M-I-PRA Specifications
| Product Type | 100BASE-T1 Ethernet PHY Transceiver |
| Standard Compliance | IEEE 802.3bw-2015 |
| Data Rate | 100 Mbit/s full duplex |
| MAC Interfaces | MII, RMII (RGMII not supported on M-variant) |
| Special Modes | Reverse MII (back-to-back PHY connection) |
| Reference Clock Output | Optional 50 MHz (RMII), 125 MHz (RGMII, LAN8770R only) |
| Management Interface | SMI (Serial Management Interface) |
| Media | Single Unshielded Twisted Pair (UTP) |
| Transceiver Channels | 4/4 (transmit/receive) |
| Core Supply Voltage | 1.1 V |
| I/O Supply Voltage | 3.3 V |
| Operating Temperature | -40C to +85C |
| Package | 32-VQFN (5x5 mm) with exposed pad, wettable flanks |
| Mounting Type | Surface Mount |
| Packaging Type | Tray |
| RoHS Status | Compliant |
LAN8770M-I-PRA 32-vqfn (5x5 mm) with exposed pad, wettable flanks Pin Configuration Guide
Pin configuration for LAN8770M-I-PRA (32-vqfn (5x5 mm) with exposed pad, wettable flanks 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 LAN8770M-I-PRA.
Refer to the datasheet for full pin configuration.
Typical Applications
LAN8770M-I-PRA is suitable for 6 applications: Automotive ECU Networking, ADAS Camera and Sensor Links, 100BASE-TX to 100BASE-T1 Media Conversion, Industrial Single-Pair Ethernet Backbones, Embedded Systems Teaching and Development Boards, Battery Management and Vehicle Charging Infrastructure.
Automotive ECU Networking
The LAN8770M-I/PRA is purpose-built for in-vehicle ECU-to-ECU communication: 100BASE-T1 per IEEE 802.3bw-2015 carries 100 Mbit/s full-duplex over a single unshielded twisted pair, cutting harness weight and connector count versus 100BASE-TX two-pair cabling. The -40C to +85C operating range and wettable-flank 32-VQFN package address automotive assembly inspection requirements. Interfacing an MCU's MII or RMII MAC to the PHY with a 50 MHz RMII reference clock output removes an external oscillator in many designs. Line-side design must follow the single-pair termination and isolation network from the Microchip reference schematic to meet EMC requirements.
Recommended
ADAS Camera and Sensor Links
ADAS cameras, radar, and lidar modules need a lightweight, high-integrity 100 Mbit/s link back to the domain controller. The LAN8770M-I/PRA delivers this over one UTP pair, where its integrated DSP equalization sustains the link across automotive cable lengths, and the 1.1 V core with 3.3 V I/O integrates cleanly into sensor-module power trees. The SMI management interface allows the host to monitor link status and diagnose faults in the field. Because sensor modules are space-constrained, the 5x5 mm QFN footprint and single-pair cabling both reduce module volume relative to multi-pair Ethernet solutions.
Recommended
100BASE-TX to 100BASE-T1 Media Conversion
Microchip's EVB-LAN8770M_MC evaluation board demonstrates the flagship use of the M-variant: connecting two PHYs back-to-back so that Reverse MII mode links the LAN8770M's MII directly to a second PHY without any MAC, converting between conventional 100BASE-TX (two-pair) and automotive 100BASE-T1 (single-pair). This enables test benches, diagnostic tools, and retrofit gateways that bridge legacy twisted-pair Ethernet infrastructure to single-pair automotive networks. The optional 50 MHz clock output synchronizes the RMII side, keeping the converter clocking simple and BOM-light.
Recommended
Industrial Single-Pair Ethernet Backbones
Industrial automation is adopting single-pair Ethernet for compact actuators, drives, and IIoT sensors where full four-pair cabling is unjustified. The LAN8770M-I/PRA provides the same 100 Mbit/s single-pair link with MII/RMII flexibility to attach to virtually any embedded processor, and its -40C to +85C rating covers cabinet and light-outdoor environments. The SMI interface supports remote register monitoring for predictive-maintenance telemetry. Using a single twisted pair also simplifies the transition to Power over Data Lines topologies when paired with external PoDL power circuitry, reducing panel wiring complexity.
Recommended
Embedded Systems Teaching and Development Boards
The LAN8770M-I/PRA suits university and training development boards: the 5x5 mm QFN is hand-assemblable with care, Microchip publishes complete evaluation-board user guides (EVB-LAN8770M_MC, EVB-LAN8770-RMII, document series 50002978A/50002979A), and the MII/RMII interfaces connect directly to popular MCU evaluation kits. The optional 50 MHz reference clock output eliminates external crystal timing complexity on the RMII side, letting students focus on protocol behavior rather than clock trees. Reverse MII back-to-back demonstrations make link-layer concepts visible on an oscilloscope without needing a MAC in the loop.
Recommended
Battery Management and Vehicle Charging Infrastructure
EV battery packs and charging stations increasingly use single-pair Ethernet for stacked-module communication, replacing CAN for higher bandwidth telemetry. The LAN8770M-I/PRA provides a deterministic 100 Mbit/s link over a single pair that routes easily through pack harnesses, while its wide -40C to +85C temperature rating accommodates pack-adjacent electronics. The 1.1 V core keeps PHY power draw low, important in always-on monitoring chains, and SMI register access lets a central controller poll module health. Standard IEEE 802.3bw-2015 compliance ensures interoperability with automotive charging-communication ecosystems.
Recommended
Recommended Products Summary
Engineering reference data for LAN8770M-I-PRA — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LAN8770R-I/PRA |
|---|---|---|
| Package | 32-VQFN (5x5 mm), exposed pad, wettable flanks | 32-VQFN (5x5 mm) - same package family |
| Brand | Microchip Technology | Microchip Technology |
| Ethernet Standard | 100BASE-T1 (IEEE 802.3bw-2015) | 100BASE-T1 (IEEE 802.3bw-2015) |
| MAC Interfaces | MII, RMII | MII, RMII, RGMII |
| Reference Clock Output | 50 MHz (RMII) | 50 MHz and 125 MHz (RGMII) |
| Operating Temperature | -40C to +85C | -40C to +85C |
Key Differentiators
- Reverse MII back-to-back mode (vs LAN8770R-I/PRA)
- Lowest-cost RGMII-free pin count (vs LAN8770R-I/PRA)
- Integrated 50 MHz RMII clock output (vs Generic PHYs requiring external oscillator)
Design Notes
The 32-VQFN exposed pad is the primary ground return for the PHY's analog circuitry and must be soldered to a solid ground plane via an array of thermal vias - it is not optional for electrical performance, only for thermal. The wettable-flank package sides allow reliable AOI solder-joint inspection required in automotive assembly. Place the single-pair termination/isolation network exactly per the Microchip reference schematic; component placement symmetry on the differential line pair is critical for return-loss compliance with IEEE 802.3bw-2015.
The device requires a 1.1 V core rail and a 3.3 V I/O rail. The 1.1 V core supplies the PHY analog front end, so it should come from a low-noise LDO or well-filtered buck stage; switching-regulator ripple on this rail can degrade the transmit eye diagram. Follow the decoupling network in the manufacturer reference design and sequence the 1.1 V rail before or with the 3.3 V rail as specified in the datasheet power-up requirements.
The LAN8770M does not support RGMII - only MII and RMII. Designs requiring RGMII must use the LAN8770R variant, so confirm the MAC interface early. For RMII operation, use the PHY's 50 MHz reference clock output or supply an external 50 MHz clock as the datasheet specifies; mismatched clocking is the most common cause of RMII link failure. Also verify SMI address strapping pins are not left floating, or register access may collide between multiple PHYs on the same management bus.
Compliance Information
JLCPCB listing marks the part ROHS. REACH, AEC-Q100 qualification level, and halogen-free status not stated in the provided data - verify on the Microchip product page.
