PoDL for Ethgernet-APL

Hi MaxBess ,

Are you designing a circuit for an intrinsic safe area? Let me elaborate my question here, the APL uses the 10BASE-T1L Ethernet physical for data, but has specific requirements for delivering power over the same cable, defines specific network topologies, and also specific requirements for the end devices to enable them to be intrinsic safe for operation in explosive environments.

For instance, an APL device will be compatible with the IEEE802.3cg device but an IEEE802.3cg device will not necessarily be APL compliant.

If you are looking for an intrinsic safe area application then, the CN0575 is not suitable for an APL application. I would recommend instead the DEMO-ADIN1100D2Z as a starting reference which has a power source and classes following the APL requirement but the hardware is not fully compliant with APL. A minimum of two set of free-wheeling diode in reverse bias are expected at the power coupling inductors, they are required to avoid any sparks from connecting/disconnecting the cable. 

If your application requires 10BASE-T1L with PoDL using the standard IEEE802.3cg, also called SPOE, then yes the CN0575 can be a reference design for the powered device (PD), However the DEMO-ADIN1100D2Z mentioned above is also SPOE compatible as a Power Source (PSE).

Regards,

Olivier

Hi Olivier,

Thanks for your reponse, it clarified a lot!

The system that I'm designing is a proof of concept (PoC) that will function as an APL Field Device (like the Hockey Puck, https://www.analog.com/en/resources/media-center/videos/6368645125112.html, but is wasn't able to find a reference design for this product), so the circuit I'm designing isn't going to be placed in a intrinsic safe area yet. So the design of the PoC can be a bit more robust and component values ​​have a little bit more leeway.

However, the PoC will be connected to an APL field switch so therefore the PoC must be compliant with the APL standard for power class A. Looking at the design of the DEMO-ADIN1100D2Z, does that also imply that the APL field device PD must support SCCP? I was hoping I can use the LTC9111 for SCCP communication.

I hope to hear from you soon.

Best regards,

Max

Hi Max,

Thank you for the explanation

The LTC9111 is the powered device (PD) in the SPOE following the IEEE802.3cg, therefore it does not support the different classes of APL. As stated before APL has specific requirement on delivering power over the cable. It is closer to an engineered power following a standard (here APL in this instance). However SCCP is specific to the IEEE802.3cg standard thus not suitable for APL.

SCCP is a protocol where both PSE and PD will auto-negotiate the required power class, but this wouldn't be possible on an APL application. Both voltage and power rating are selected beforehand, leaving no other possibilities for safety purposes.

For a field device, the HockeyPuck is the only APL-compliant board design we have but it is not released yet.

Regards,

Olivier

Hi Olivier,

Thank you for the quick response and clarification.

If you want, I can send you updates on the progress of the project. Also, if possible, I would like to be informed when the HockeyPuck gets released.

Thank you again for your time 

Best regards,

Max