Low Power Wake-on-LAN
Challenges and Solutions
Electronic systems are increasingly required to consume minimal amounts of power in all modes, particularly in standby mode. For example, EU eco-design requirements state that household and office appliances that must consume no more than 0.5 W of power in standby mode.
The typical solution uses a System-on-a-Chip (SoC) or ASIC that is always on. Therefore, total system standby power is typically in a range of ~ 2 – 8 W, well above the EU eco-design requirements.
Silicon Labs has a solution that allows a systems designer to switch off all the power hungry components, but maintain the Wake-on-LAN (WoL) capability that is required in standby mode. The implementation uses a tiny single-chip MCU that fits into existing PCB space. Silicon Labs has already developed all of the software.
The system can now be maintained in a low power sleep state and only woken-up when it receives a particular message (known as a "magic packet") on the Local Area Network (LAN). The MCU monitors the MII bus that connects an Ethernet PHY to an Ethernet MAC. The inclusion of the MCU in the system allows the MAC to be put into a low power sleep mode. The MAC is woken-up when the MCU detects a specific message containing its MAC address (the "magic packet") and sends a wake-up signal. The MCU therefore provides a way to add low power capability to the system.
Low Power Wake-on-LAN Solutions
The low power Wake-on-LAN solution allows electronic systems to meet energy saving eco-design requirements and get the system into production fast.
- All the power-hungry components can be switched off while the system maintains a Wake-on-LAN capability
- The functionality can be easily added to existing systems to provide the low power Wake-on-LAN function. No major re-design of the system or SoC components are required.
This solution is optimized for low power consumption and size.
- Power consumption for the Wake-on-LAN function is only 42 mW; well below the standby power budget of 0.5 W
- No additional components are required. An on-chip voltage regulator allows the solution to support from 1.8 to 5 V operation.
- Integrated on-chip precision oscillator means no external crystal is required
- Tiny 4 mm x 4 mm package that can easily fit into existing PCB space constraints