Hi,
We have used TPS23754 POE interface and Dc to Dc controller IC in the POE+ design.
We have connected two 0402 package resistors in series from CLS pin to VSS. The value of this resistors is 50 ohms and 15 ohms.
The program classification current flowing through both the resistors would be 2.5V/65ohms, which is 38.4mA. The calculated power across 50ohms is 71mW and for 15 ohms is 22mW.
The power dissipation in 50ohms resistor with 0402 package is 71mW, is higher than the original power wattage of 62.5mW for 0402 pacakge resistor.
To lower power dissipation in both 0402 package resistors I would like to use 33 ohms + 33 ohms from CLS pin to VSS.
The program classification current in this case would be 2.5V / 66 ohms = 37.8mA, which is less than the minimum current as shown in the below pic.
Using two 33 ohms 0402 package resistors the power dissipation during program classification is 47.3mW, which is less than the 62.5mW for 0402 package resistor.
Can I use 33 ohms (0402 package) + 33 ohms (0402 package) resistors between CLS pin and VSS in my POE+ design?
Regards,
KIRAN SURVE
