What are the key considerations when choosing a PHY for an industrial application?
When selecting a PHY, we should take note of the following:
1. Performance - This can be described as the latency of the PHY, a low latency PHY reduces the network cyctle time, improving the network refres time and allows more devices to be connected to the network. The network cycle time is the communication time required by the controller to both collect and update data memories of all devices. Many topologies for the industrial ethernet are typically a LINE or a RING topology, devices connections requiring two ports for data in and out. This means PHY latency is likely doubled and to make sure that performance is better, a lower latency PHY must be used.
The ADIN1300 PHY of Analog Devices has significantly lower latency.
2. Robustness - The Ethernet PHY must pass and adhere EMI/EMC standards like CISPR32, IEC61000-4-2/4/5/6. These are external radiated emissions and conducted emissions and noise sources that can contribute to a harsh operating environment, We must select a PHY that has been tested to these standards. These prevents lenghy redesign cycles to secure EMC certifications in the development flow.
THe ADIN1300 PHY on the ADIN evaluation boards has been through various EMC tests to prove its robustness.
3. Low Power - The devices in Industrial Applications are typically IP65/66 sealed from dust and moisture and hence have restricted airflow and have limited power dissipation capability. Similarly, these devices are other exposed to high operating temperature in industrial environments.This concludes that the PHY must operate at a low power.
The ADIN1300 PHY offers on the order of 30% saving in power with 330 mW of power at 100% data throughput.