LAN8770M-I/PRA - 100BASE-T1 Ethernet PHY, VQFN-32 | Microchip
MPN: LAN8770M-I/PRA ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.12 | $4.12 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
LAN8770M-I/PRA Overview
An Ethernet PHY transceiver is the physical-layer device in the network hierarchy that converts digital MAC frames into analog signals suitable for transmission over copper media. Positioned between the Ethernet MAC (typically inside an MCU, MPU, or switch) and the physical cable, the PHY handles encoding, line drivers, equalization, and clock recovery. The 100BASE-T1 standard (formerly BroadR-Reach) enables single-pair cabling at 100 Mbit/s, reducing weight and cost versus conventional two-pair 100BASE-TX.
Key features of the LAN8770M include support for standard MII and RMII MAC interfaces, an optional 50 MHz reference clock output for RMII applications, and the distinctive Reverse MII mode that allows two PHYs to be connected back-to-back for media converter and bridge applications. An integrated SMI (Serial Management Interface) provides rapid register access and configuration.
Technically, the device integrates the analog line drivers, adaptive equalizers, and echo cancellation needed for single-pair operation, while the digital core handles 4B/5B encoding and interface multiplexing. The 'M' variant is specifically the Reverse MII member of the LAN8770 family; the LAN8770R adds RGMII support with an optional 125 MHz clock output.
Typical applications include automotive in-vehicle networking (camera links, ECUs, gateways), industrial media converters such as Microchip's EVB-LAN8770M_MC 100BASE-TX to 100BASE-T1 converter reference, factory automation sensor nodes, and compact IoT edge devices where single-pair cabling saves harness cost.
Design consideration: the 32-VQFN exposed pad must be soldered to a solid ground plane for thermal and EMI performance, and the RMII reference clock routing requires length-matched traces. Verify the exact supply rails, current consumption, and MAC interface voltage levels in the manufacturer datasheet before finalizing power tree design.
This page synthesizes distributor pricing, family-level drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with all data verified as of 2026-10-19.
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:
LAN8770-I/PRA
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LAN8770M-E/PRA
✅ Drop-In📋 Reference alternative (not in catalog)
LAN8770R-I/PRA
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LAN8770M-I/PRA Specifications
| Network Standard | 100BASE-T1 (IEEE 802.3bw-2015) |
| Data Rate | 100 Mbit/s |
| MAC Interface | MII, RMII, Reverse MII (LAN8770M) |
| Media | Single Unshielded Twisted Pair (UTP) |
| Duplex | Full |
| Number of Ports | 1 |
| Transceiver Count | 4/4 |
| Reference Clock Output | 50 MHz (RMII) |
| Management Interface | SMI (Serial Management Interface) |
| Operating Temperature | -40C to +85C (industrial, -I suffix) |
| Package | 32-VQFN (5x5 mm), exposed pad, wettable flanks |
| Mounting Type | Surface Mount |
| Compliance Standard | IEEE 802.3bw-2015 |
LAN8770M-I/PRA 32-vqfn (5x5 mm), exposed pad, wettable flanks Pin Configuration Guide
Pin configuration for LAN8770M-I/PRA (32-vqfn (5x5 mm), 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 In-Vehicle Networking, Media Converter - 100BASE-TX to 100BASE-T1, Industrial Automation Sensor Nodes, Automotive Camera and Imaging Links, Compact IoT Edge Devices, Test and Measurement Instrumentation.
Automotive In-Vehicle Networking
The LAN8770M-I/PRA targets 100BASE-T1 (IEEE 802.3bw-2015), the dedicated automotive Ethernet standard that carries 100 Mbit/s over a single unshielded twisted pair, cutting cable weight and connector cost versus two-pair 100BASE-TX. It fits camera modules, ADAS sensor nodes, ECUs, and domain gateways where the RMII interface with 50 MHz reference clock output connects directly to automotive MCUs. The industrial -40C to +85C range and wettable-flank VQFN-32 package support automotive assembly and inspection. Place it between the MAC and the single-pair harness with the vendor-recommended common-mode choke and AC-coupling network; unlike 100BASE-TX, no magnetics transformer in the classic sense is required, but the physical-layer termination network must follow the Microchip reference design to pass EMC.
Recommended
Media Converter - 100BASE-TX to 100BASE-T1
The defining feature of the LAN8770M is Reverse MII mode, which allows two PHYs to connect back-to-back without any MAC between them. This makes the part the natural choice for media converters bridging legacy two-pair 100BASE-TX infrastructure to single-pair 100BASE-T1 automotive or industrial links. Microchip's own EVB-LAN8770M_MC evaluation board demonstrates exactly this topology, pairing a standard PHY with the LAN8770M over their reverse-connected MII pins. Performance consideration: back-to-back operation introduces no protocol translation latency because frames pass at the MAC-layer digital level, but both PHYs must be clock-domain aligned per the reverse MII configuration in the user's guide (document 50002979A), so follow the reference clock architecture carefully.
Recommended
Industrial Automation Sensor Nodes
Single-pair Ethernet is spreading into factory automation because it converges 100 Mbit/s data and optional power over one thin cable, ideal for compact sensor and actuator nodes mounted on robots, conveyors, and machine frames. The LAN8770M-I/PRA's RMII interface connects to cost-optimized MCUs while the SMI interface allows runtime configuration from the host processor. Its industrial -40C to +85C rating covers typical shop-floor enclosures, and the 5x5 mm VQFN keeps node PCB area small. Engineering consideration: in electrically noisy factory environments, follow the Microchip reference termination on the single-pair line and maintain solid ground planes under the exposed pad - the integrated equalization handles cable loss, but layout-induced common-mode noise is the primary residual EMC risk.
Recommended
Automotive Camera and Imaging Links
Single-pair 100BASE-T1 at 100 Mbit/s is sufficient for compressed video streams from surround-view and rear-view cameras, making the LAN8770M-I/PRA a cost-effective PHY for automotive imaging modules. The camera-side SoC connects via RMII using the PHY's 50 MHz reference clock output, minimizing oscillator count on the compact camera PCB. The wettable-flank VQFN-32 package enables automated optical inspection demanded by Tier-1 assembly lines, and the single twisted pair dramatically simplifies the camera harness. Design trade-off: raw uncompressed 1 MPix video exceeds 100 Mbit/s, so the camera must apply compression; verify bandwidth budgeting end-to-end, and consider higher-rate 1000BASE-T1 PHYs for high-resolution imaging chains.
Recommended
Compact IoT Edge Devices
Wired single-pair Ethernet gives IoT edge devices deterministic, power-efficient connectivity without wireless stack complexity. The LAN8770M-I/PRA's 5x5 mm VQFN footprint and RMII MAC interface suit dense edge controllers, smart-building panels, and PoE-powered sensor hubs where board space is constrained. The integrated SMI interface enables the host MCU to monitor link status and diagnostics at runtime. Because only one twisted pair is routed to the connector, the PCB can use inexpensive single-lane cabling to remote junctions. Power consideration: Ethernet PHYs draw continuous current while linked; confirm the exact consumption in the datasheet when budgeting for energy-harvesting or battery-backed nodes, and use the PHY's power-down modes between active periods where the application permits.
Recommended
Test and Measurement Instrumentation
Bench and rack instruments increasingly expose Ethernet for remote control, data streaming, and LXI-style integration, and 100BASE-T1 single-pair ports are appearing on automotive test fixtures that must speak the vehicle's native network standard. The LAN8770M-I/PRA serves both roles: as the standard instrument PHY via RMII/MII, and as the vehicle-interface PHY in bus simulation and remaining-bus-simulation tools. The SMI register access supports scripted configuration from the instrument's main controller. Accuracy consideration: for conformance testing of other 100BASE-T1 devices, use the EVB-LAN8770M_MC reference design as the known-good link partner and verify the PHY's master/slave configuration is fixed, since auto-negotiation of master-slave roles can obscure test repeatability.
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 | LAN8770-I/PRA | LAN8770M-E/PRA | LAN8770R-I/PRA |
|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Network Standard | 100BASE-T1 (IEEE 802.3bw-2015) | 100BASE-T1 (IEEE 802.3bw-2015) | 100BASE-T1 (IEEE 802.3bw-2015) | 100BASE-T1 (IEEE 802.3bw-2015) |
| MAC Interface | MII, RMII, Reverse MII | MII, RMII | MII, RMII, Reverse MII | MII, RMII, RGMII |
| Reverse MII Mode | Yes | No | Yes | No |
| RGMII Support | No | No | No | Yes (125 MHz clock output) |
| Reference Clock Output | 50 MHz (RMII) | 50 MHz (RMII) | 50 MHz (RMII) | 50 MHz (RMII) / 125 MHz (RGMII) |
Key Differentiators
- Reverse MII back-to-back PHY connection (vs LAN8770-I/PRA)
- Single-pair 100 Mbit/s cabling savings (vs Two-pair 100BASE-TX PHYs (e.g., KSZ8081 family))
- Extended temperature option within the same footprint (vs LAN8770M-E/PRA)
Design Notes
The 32-VQFN 5x5 mm package has an exposed pad that must be soldered to a continuous ground plane - it is the primary ground return and thermal path for the PHY. Use an array of vias (typically 5x5 or more) under the pad to tie it to inner ground layers. The wettable flanks are designed for AOI inspection in automotive assembly; ensure the stencil design leaves sufficient solder volume on the side terminations. Per the DiGi-Electronics product detail, this package variant was specifically chosen for space-constrained PCB designs while maintaining thermal and electrical performance.
RMII operation depends on a clean 50 MHz reference clock. When using the PHY's clock output to drive the MAC, route the clock as a short, length-matched trace with a series termination resistor (typically 22 to 33 ohm) to control ringing. Avoid routing the clock adjacent to the single-pair 100BASE-T1 line driver pins, as coupling between them degrades both jitter and EMC. The MII/RMII data bus should follow standard high-speed practice: short stubs, solid reference plane underneath, and consistent trace impedance.
Do not assume cross-family interchangeability: the LAN8770 (MII/RMII), LAN8770M (adds Reverse MII), and LAN8770R (adds RGMII) have different MAC-side pin functions despite the same 100BASE-T1 analog physical layer. Substituting one for another will fail at the digital interface even though the cable side behaves identically. Also confirm master/slave PHY configuration early - single-pair links require one master and one slave, and an incorrect strap or register setting is the most common first-bring-up failure. Validate the design on the EVB-LAN8770M_MC evaluation board before layout freeze.
Compliance Information
Compliance details were not present in the provided web data. Verify RoHS/REACH status on the official Microchip LAN8770 product page or product change notifications before order placement.
