Tool/software:
HI Team
Can you help to review the schematic design?
Input：PoE 802.3af/at 37-57V, 25Wmax
Output：5V2A@802.3af； 5V3A/9V2.22A@802.3at
To identify the POE by TPS2378 T2P pin output voltage level to U603 pin1，when the voltage level is high，it is 802.3af ，if the voltage level is low，it is 802.3at
Hi Marry,
Thanks for reaching out!
I want to confirm the PD chip used is TPS2372-3, not TPS2378.TPH and TPL and be used to indicate AF (TPH=Hi-Z, TPL=Hi-Z) and AT (TPH=Hi-Z, TPL=Low).
Please see the comments on the PoE PD circuit only:
1. To enable the auto maintain power signature, AMPS_CTL needs a 1/4W or larger power rating at R605. Normally 1206 or larger.
To disable the auto maintain power signature, you need to DNP R605.
2. In most of cases, autoclass function is not needed, unless the application is constant load like LED lighting. DNP R607 to disable autoclass function.
3. PG pin is recommended used to avoid downstream circuit draw too much current during PD inrush.
4. PC601 is optional to use 33uF to meet PoE longest 250us 802.3BT transient requirement.
5. Isolated DC/DC is optional to meet 802.3BT standard isolation requirement.
Best regards,
Diang
