ZHCSMU0D July 2009 – December 2020 TPS23753A
A TVS across the rectified PoE voltage per Figure 9-1 must be used. For general indoor applications, TI recommends an SMAJ58A or a part with equal to or better performance. If an adapter is connected from VDD1 to RTN, as in ORing option 2 above, voltage transients caused by the input cable inductance ringing with the internal PD capacitance can occur. Adequate capacitive filtering or a TVS must limit this voltage to be within the Absolute Maximum Ratings. Configurations that use DVDD as in Figure 8-10 may require additional protection against ESD transients that would turn DVDD off and force all the voltage to appear across the internal hotswap MOSFET. CVDD and DRTN per Figure 8-10 provide this additional protection.
Outdoor applications require more extensive protection to lightning standards.