With the VBUS054CV-HS3 a double, high speed USB-port can be protected against transient voltage signals. Negative transients will be clamped close below the ground level while positive transients will be clamped close above the 5 V working range. An avalanche diode clamps the supply line (VBUS at pin 5) to ground (pin 2). The high speed data lines, D1+, D2+, D1- and D2- , are connected to pin 1, 3, 4 and 6. As long as the signal voltage on the data lines is between the ground- and the VBUS -level, the low capacitance PN-diodes offer a very high isolation to VBUS, ground and to the other data lines. But as soon as any transient signal exceeds this working range, one of the PN-diodes gets in the forward mode and clamps the transient to ground or the avalanche break through voltage level.