Hello,
I am trying to understand TPS2379EVM schematic. What is the purpose of R14, D12, and Q3? It seems to me like when RTN voltage drops to VSS after initiation sequence completes, Q3 will be on connecting SRTN to RTN any way. Will connecting J5 make any difference from not connecting it? And will J5 be less meaningful if I use CDB to soft-start my DC/DC converter?
One more unrelated question: What does the bypass capacitor C8 do? Isn't just C2 enough?
For classification problem, the load for my PoE is a stepper motor that will require maximum power sourceable 25.5W (class 4) 0.6A at 42.5V out of TPS2379 when actuated. But when it is not actuated the load will be smaller (in class 0 range). So my question is: in such a dynamic load demand situation, do I need DLL classification to tell PSE when PD requires power in class 0 and class 4 ranges? Is the 2-event physical layer classification alone enough?
If DLL is needed, how can I implement it to comply with 802.3at standard?
Do all 802.3at-compliant PSEs support DLL classification?
Thank you!
Naputt
