LAN8742A

Part: LAN8742A/LAN8742Ai — Microchip Type: Small Footprint RMII 10/100 Ethernet Transceiver Description: Low-power 10BASE-T/100BASE-TX physical layer (PHY) transceiver with variable I/O voltage, compliant with IEEE 802.3 and 802.3u standards, supporting RMII interface, HP Auto-MDIX, and Wake on LAN (WoL).

Operating Conditions:

• Supply voltage: +1.8 V to +3.3 V (LVCMOS Variable I/O voltage range)
• Operating temperature: 0°C to +70°C (Commercial) or -40°C to +85°C (Industrial)

Absolute Maximum Ratings:

Key Specs:

• Ethernet standards: IEEE 802.3/802.3u (Fast Ethernet), ISO 802-3/IEEE 802.3 (10BASE-T)
• I/O voltage range: +1.8 V to +3.3 V
• Digital interface pin tolerance: 3.6 V
• Crystal frequency: 25 MHz
• RBIAS resistor: 12.1 kΩ (1%)
• REFCLKO output frequency: 50 MHz (derived from 25 MHz crystal)

Features:

• Single-Chip Ethernet Physical Layer Transceiver (PHY)
• Cable diagnostic support
• Wake on LAN (WoL) support
• flexPWR technology with flexible power management and integrated 1.2 V regulator
• HP Auto-MDIX support
• Supports Reduced Media Independent Interface (RMII)
• Auto-negotiation and automatic polarity detection and correction
• Various low power modes
• Integrated power-on reset circuit
• Two status LED outputs
• Serial Management Interface (SMI) for register access

Applications:

• Set-Top Boxes
• Networked Printers and Servers
• Test Instrumentation
• LAN on Motherboard
• Embedded Telecom Applications
• Video Record/Playback Systems
• Cable Modems/Routers
• DSL Modems/Routers
• Digital Video Recorders
• IP and Video Phones
• Wireless Access Points
• Digital Televisions
• Digital Media Adapters/Servers
• Gaming Consoles
• POE Applications

Package:

• 24-pin VQFN (4 x 4 x 0.9 mm height)

• Set-Top Boxes
• Networked Printers and Servers
• Test Instrumentation
• LAN on Motherboard
• Embedded Telecom Applications
• Video Record/Playback Systems
• Cable Modems/Routers
• DSL Modems/Routers
• Digital Video Recorders
• IP and Video Phones
• Wireless Access Points
• Digital Televisions
• Digital Media Adapters/Servers
• Gaming Consoles
• POE Applications

(Refer to Microchip Application Note 17.18)

FIGURE 2-1: 24-VQFN PIN ASSIGNMENTS (TOP VIEW)

Note: When a lower case 'n' is used at the beginning of the signal name, it indicates that the signal is active low. For example, nRST indicates that the reset signal is active low.

Note: The buffer type for each signal is indicated in the BUFFER TYPE column. A description of the buffer types is provided in Section 2.2.

Note 1: When powering this device from laboratory or system power supplies, it is important that the absolute maximum ratings not be exceeded or device failure can result. Some power supplies exhibit voltage spikes on their outputs when AC power is switched on or off. In addition, voltage transients on the AC power line may appear on the DC output. If this possibility exists, it is suggested that a clamp circuit be used.

• 2: This rating does not apply to the following pins: XTAL1/CLKIN, XTAL2, RBIAS.
• 3: This rating does not apply to the following pins: RBIAS.

Stresses exceeding those listed in this section could cause permanent damage to the device. This is a stress rating only. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Functional operation of the device at any condition exceeding those indicated in Section 5.2, "Operating Conditions*" or any other applicable section of this specification is not implied. Note, device signals are NOT 5.0 V tolerant unless specified otherwise.

Note: Thermal parameters are measured or estimated for devices in a multi-layer 2S2P PCB per JESD51.

This section provides typical application diagrams for the following:

• Simplified System Level Application Diagram
• Power Supply Diagram (1.2 V Supplied by Internal Regulator)
• Power Supply Diagram (1.2 V Supplied by External Source)
• Twisted-Pair Interface Diagram (Single Power Supply)
• Twisted-Pair Interface Diagram (Dual Power Supplies)