Reduce EOS Failures With Enhanced Internal Surge Protection for PoE Applications
A higher level of surge protection can reduce Electrical Overstress (EOS) failures in a system. Adding external surge components adds cost to the system. The seventh generation PD77728 Power over Ethernet Power Sourcing Equipment (PoE PSE) device doubles the level of integrated surge protection to lower external component costs.
Challenges in Analyzing Device Failures in Diverse Applications
Clients design our products into thousands of different applications and understanding the working conditions and corner cases for all these applications is quite challenging. Events occur in an application that may cause an integrated circuit (IC) to fail and the client will submit that failed device to us for a device failures analysis (FA).
FA Results Show EOS
Most often, the result of the FA shows that device was manufactured properly, and the failure mode was the dreaded electrical over stress or EOS. An EOS failure means the integrated circuit was subjected to voltage and/or current conditions that exceed the maximum allowed ratings for the device. At this point, the client will ask our application engineers to analyze their circuit to help determine the source of the EOS.
Surges Can Cause EOS
Electrical surge events are very high voltages (in the thousands of volts) for short durations of time (microseconds). When discussing surge events, a popular example is an external cause such as a lightning strike.
More common surges are internal events like an air conditioning unit turning on or when the drive motor kicks on in the beloved office printer that seems to jam more often than print.
Many cables run through the office walls close to the power lines and power surges can easily couple to the Ethernet cable. Any device connected to the Ethernet cable can be subjected to surge.
Add Electrical Surge Protection
Surge protection circuitry diverts the high voltages to earth ground thus bypassing the integrated circuit. The circuitry is typically external to the main application circuitry. This circuitry adds cost. The client will run a cost for performance analysis and many times the external surge components are removed or “de-populated” during production to save cost.
Integrated Surge Protection
The current generation of PoE PSE devices have internal surge protection of 1kV per the International Electrical Commission IEC 61000-4-5 standard on surge immunity. This is a minimal level that still protects the PoE circuitry in applications where no external surge components are used.
Surge events and EOS still occur so we listened to our clients and improved the internal surge protection on our new 7th generation PD77728 PSE device. The surge protection level has been doubled to 2kV.
Using the new PD77728 with enhanced surge protection for PoE PSE applications will help clients design and manufacture more robust systems even when cost saving reduces those external surge components.
Microchip PoE Solutions
Microchip has PoE solutions for both the power sourcing side (PSE) and the powered device side (PD) of the Ethernet cable.
- Power Sourcing Equipment (PSE) ICs for switches, routers and PoE injectors.
- Powered Device (PD) and Ideal Diode Bridge (IDB) ICs for any device that is always connected to the Ethernet cable and consumes less than 90W of power.
Visit our PoE web page to learn more about Microchip PoE technology, PoE integrated circuits and PoE comprehensive system solutions.