LAN8740A-EN - 10/100 Ethernet PHY | Microchip Technology
MPN: LAN8740A-EN ✓ ActiveLAN8740A-EN Overview
An Ethernet PHY is the physical-layer interface between a network media-access controller and twisted-pair cabling. Within the Ethernet interface hierarchy, the PHY connects a digital MAC to the analog 10BASE-T or 100BASE-TX line interface. The LAN8740A supports IEEE 802.3, IEEE 802.3u, and IEEE 802.3az Energy Efficient Ethernet operation, placing it in the low-power 10/100 Ethernet transceiver category.
Key features include support for both straight-through and crossover cables through HP Auto-MDIX, automatic speed and duplex-mode selection, variable I/O voltage, and cable diagnostics that can reduce installation and troubleshooting costs. Commercial and industrial temperature variants are offered because the LAN8740A/LAN8740Ai family is specified from 0°C to 70°C or -40°C to 85°C, depending on the selected ordering option.
The device is designed for embedded systems requiring a compact 10/100 Ethernet interface rather than gigabit data rates. MII support offers a parallel host interface for designs using the larger pin assignment, while RMII reduces the number of host-side signals and can simplify connections to controllers that support that interface. Auto-negotiation allows the PHY to select the best supported speed and duplex combination with the link partner.
Typical uses include industrial controllers, embedded network equipment, set-top and communications appliances, and connected industrial products requiring a compact Ethernet front end. A 5 mm by 5 mm surface-mount package supports compact board layouts, but correct magnetics, termination, reference-clock implementation, decoupling, and high-speed layout remain essential for reliable links.
Designers should follow the manufacturer datasheet and its reference circuit for the 25 MHz crystal or oscillator network, magnetic isolation, center-tap capacitors, and PCB layout. The 5 mm by 5 mm package also requires careful thermal assessment when the PHY operates continuously in an enclosed system.
This page consolidates manufacturer specifications, distributor availability information, package details, and verified cross-reference evidence into an engineering-oriented guide. It also distinguishes documented functions from parameters that still require confirmation from the complete manufacturer datasheet or a detailed PCB design review.
Drop-in alternatives for LAN8740A-EN — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LAN8740A-EN (same form factor and footprint) — differing in Auto-Negotiation, Cable Support, Package.
LAN8710A-EZC-TR
✅ Drop-InContact for price
View Datasheet →LAN8740A-EN Specifications
| Product Type | 10BASE-T/100BASE-TX Ethernet PHY transceiver |
| Supported Data Rates | 10 Mbps and 100 Mbps |
| Host Interface | MII and RMII |
| Network Standards | IEEE 802.3, IEEE 802.3u, and IEEE 802.3az |
| Energy Efficient Ethernet | Supported |
| Cable Support | 10BASE-T and 100BASE-TX |
| Auto-Negotiation | Supported for speed and duplex mode |
| Auto-MDIX | HP Auto-MDIX supported |
| Cable Diagnostics | Supported |
| Loopback | Deterministic loopback delay |
| I/O Voltage | Variable |
| Commercial Temperature Range | 0°C to 70°C |
| Industrial Temperature Range | -40°C to 85°C |
| Package | 32-pin SQFN, 5 mm x 5 mm |
| Mounting Type | Surface Mount |
| Transceiver Count | 1 |
LAN8740A-EN 32-pin sqfn, 5 mm x 5 mm Pin Configuration Guide
Pin configuration for LAN8740A-EN (32-pin sqfn, 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 LAN8740A-EN.
Refer to the datasheet for full pin configuration.
Typical Applications
LAN8740A-EN is suitable for 6 applications: Industrial Ethernet Controllers, Embedded Communication Equipment, IoT Edge Gateways, Network Appliances, Set-Top and Media Devices, Test and Measurement Equipment.
Industrial Ethernet Controllers
The LAN8740A-EN is suitable for compact industrial controllers that require 10 Mbps or 100 Mbps Ethernet rather than gigabit throughput. Its 32-pin 5 mm by 5 mm SQFN package limits board area, while MII and RMII support allows selection of the host interface that best matches the embedded controller. Auto-negotiation selects the supported speed and duplex mode automatically. For an industrial deployment, verify the exact -EN temperature grade and use manufacturer-recommended Ethernet magnetics, isolation components, and a protected physical-layer layout.
Recommended
Embedded Communication Equipment
The LAN8740A-EN can provide the copper Ethernet front end for embedded gateways, communications appliances, and access equipment operating at 10 or 100 Mbps. RMII is useful when conserving host-controller pins, while MII supports conventional parallel MAC implementations. HP Auto-MDIX allows field-installed straight-through or crossover cables to be used without manual software configuration. The design should include the manufacturer-specified 25 MHz clock source, magnetics, center-tap capacitors, and controlled return paths to maintain a reliable 100BASE-TX link.
Recommended
IoT Edge Gateways
The LAN8740A-EN fits IoT edge gateways that require a compact, wired network connection for configuration, telemetry, or local management. Its variable I/O voltage can simplify host-interface integration when matched correctly to the system supply and controller levels, although the complete datasheet must be used to validate every supply domain. IEEE 802.3az support can reduce link energy use when the host and network infrastructure support the applicable features. The small package helps conserve board area, but thermal design and Ethernet-magnetics isolation remain critical.
Recommended
Network Appliances
The LAN8740A-EN can serve as the 10/100 Ethernet physical layer in network appliances where a wired management or service port is required. MII support is valuable for designs unable to use RMII, while auto-negotiation improves interoperability with existing switches and endpoint equipment. Cable diagnostics provide additional installation and fault-isolation information, and deterministic loopback delay supports repeatable system testing. Engineers should preserve the recommended separation between PHY, magnetics, and connector while observing the manufacturer's high-speed layout guidance.
Recommended
Set-Top and Media Devices
The LAN8740A-EN is applicable to set-top boxes and media devices that require a compact wired connection for control, service access, or content networking at 10 or 100 Mbps. Its 5 mm by 5 mm SQFN package supports space-constrained consumer-electronics boards, and the selectable MII or RMII host interface offers design flexibility. The PHY's auto-negotiation and HP Auto-MDIX features reduce configuration requirements in installed equipment. Compliance, EMC, and production availability should be confirmed for the target market rather than inferred from the family name.
Recommended
Test and Measurement Equipment
The LAN8740A-EN can provide a network control and service interface in test, measurement, and diagnostic equipment. Deterministic loopback delay is useful for repeatable timing evaluation, while cable diagnostics can help identify installation faults and reduce commissioning time. MII operation may simplify integration with laboratory controllers that lack RMII, whereas RMII can lower pin count in compact portable instruments. For a production instrument, verify the exact temperature grade, clock accuracy, isolation strategy, grounding, and ESD protection required by the target enclosure and installation environment.
Recommended
Recommended Products Summary
Engineering reference data for LAN8740A-EN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LAN8710A-EZC |
|---|---|---|
| Brand | Microchip Technology | Microchip Technology |
| Package | 32-pin SQFN, 5 mm x 5 mm | 32-pin SQFN, 5 mm x 5 mm |
| Supported Data Rates | 10 Mbps and 100 Mbps | 10/100 Ethernet transceiver |
Key Differentiators
- Broader documented host-interface support (vs LAN8710A-EZC)
- Energy Efficient Ethernet capability (vs LAN8710A-EZC)
- Cable diagnostics and deterministic loopback (vs LAN8710A-EZC)
- Compact integration without changing the established footprint class (vs LAN8710A-EZC)
Design Notes
Place the PHY, Ethernet magnetics, and connector according to the manufacturer reference layout. Keep the 25 MHz clock and crystal-trace loop compact and away from Ethernet and switching-regulator high-current paths. Preserve short ground-return paths and continuous reference planes under high-speed pairs. Do not substitute a generic magnetics footprint without comparing its impedance, insertion loss, isolation, center-tap arrangement, and rated voltage with the recommended circuit.
Decouple each applicable supply domain near the associated PHY pins and provide the required bulk capacitance on the board. The verified data confirms variable I/O voltage but does not provide the complete operating-voltage table, so use the official datasheet to confirm supply sequencing, voltage limits, and which pins require external biasing. Avoid applying the variable I/O voltage to every supply domain; the internal supply and host-interface rails can have different limits.
Do not treat a shared package as proof of unconditional interchangeability. A LAN8710A-EZC substitution requires checking every power, ground, clock, strap, reset, interrupt, MII/RMII, and LED-related connection, as well as the reference clock source and Ethernet-magnetics network. Unverified differences in interrupt behavior, power requirements, cable diagnostics, Energy Efficient Ethernet, or startup timing can cause a link failure even when the land pattern appears identical.
The Ethernet magnetics provide galvanic isolation between the PHY and cable, but the implementation still requires controlled high-speed routing and proper return paths. Keep the connector and protection network close together, maintain the recommended pair geometry, and use only protection devices whose capacitance and waveform characteristics are compatible with 100BASE-TX. Validate conducted and radiated emissions on the final enclosure rather than relying only on schematic compliance.
Compliance Information
The supplied verified results identify IEEE 802.3, IEEE 802.3u, and IEEE 802.3az compliance but do not provide RoHS, REACH, lead-free, halogen-free, conflict-minerals, or AEC-Q100 declarations for LAN8740A-EN. AEC-Q100 is not applicable because this is an Ethernet interface IC rather than an automotive-qualified component.
