SLVSH00 November 2024 TPD4S480
PRODUCTION DATA
If additional IEC ESD protection is desired to be placed on either the CC or SBU lines, it is important that high-voltage ESD protection diodes be used. The maximum DC voltage that can be seen in USB PD is 50.4V, with 50.9V allowed during voltage transitions. Therefore, an ESD protection diode must have a reverse stand off voltage higher than 50.9V to prevent the diode from breakdown during a short-to-VBUS event.
Due to the fact that the Short-to-VBUS event applies a DC voltage to the CC and SBU pins, a deep-snap-back diode cannot be used unless its minimum trigger voltage is above 96V. During a Short-to-VBUS event, RLC ringing of up to twice the settling voltage can be exposed to CC and SBU, allowing for up to 48V to be exposed. Furthermore, if any capacitor derates on the CC or SBU line, greater ringing can occur. Since this ringing is hard to bound, it is recommended to not use deep-snap-back diodes. If the deep-snap-back diode triggers during the short-to-VBUS hot-plug event, it begins to operate in its conduction region. With a 48V VBUS source present on the CC or SBU line, this allows the diode to conduct indefinitely.