The ESDS304, ESDS302 devices are a passive integrated circuit that triggers when voltages are above V_BRF or below 0.7V. During ESD events, voltages as high as ±30kV (air) can be directed to ground via the internal diode network. When the voltages on the protected line fall below the trigger levels of ESDS304, ESDS302 (usually within a few nano-seconds) the devices reverts to passive.