Other Parts Discussed in Thread: , PMP7355, TPS23756
Hi,
I was wondering if there is a design guide for using TPS23753A delivering the full 13W available to a PD (802.3af) at 5.0V, 2.5A output.
I read document SLVA305 as a guide, however this explains an example delivering 5.0V at 1.4A, which is not quite enough for our applicaiton.
I have also read document SLVA306 for ORing an auxilliary wall power, and for a 12V input, we would need to use Option 2.
Our requirements are:
1. Using TPS23753A (since it is a handy small TTSOP16 part) - other recommendations in same family will be acceptable.
2. Using Coilcraft PoE13F-50 transformer - since it is the only one we have found with height 8.5mm low enough to fit in our chosen enclosure.
3. Simple design, like that shown in SLVA305. Other designs using more MOSFETs in leui of diodes looks too complicated, and will take more board area.
4. 48V PoE primary source, and auxiliary input of 12V / 24V industrial power supply. Also we would like to use this in battery / solar solutions, so a minimum operating input voltage of 10.5V is desired.
Can someone offer a starting guide?
PS: We are now focusing on PMP7355 which details a 5V @ 2A design using a POE13P-50 transformer, and inserting Dvdd between VDD and VDD1 pins, and injecting 12V into VDD1 via another diode as described in SLVU314F (TPS23753AEVM-004). However this suggests at 12V input, power is limited to 6W - why? Would reducing R18 below 0.39 ohms allow more current?
Kind Regards, Kyran McGlasson - SAGE Automation