Engineers new to over-voltage protection often question whether adding powerful transient voltage suppressors (TVS) to a non-fault protected, standard transceiver can ensure sufficient protection against short and long term over-voltages. The answer is NO because the peak transient power a TVS can absorb decreases with increasing transient duration. This is shown in the peak pulse power versus pulse width characteristic here. This diagram is taken from the data sheet of a 600 W TVS rated at 1 ms pulse width. Note that the time axis ranges from 10 μs to 10 ms with power levels dropping from 6000 W down to 200 W respectively. From this characteristic, it becomes clear that exposing a TVS to long term over-voltages will burn up the device in an instant. Therefore, to protect bus nodes against the wide range of over-voltages, fault protected transceivers are needed such as Renesas' ISL3245xE family. These devices provide protection against long-term over-voltages of up to ±60 V, and against transient over-voltages conforming to TIA/EIA-485-A, Section 4.2.6 (for 15 μs at a 1% duty cycle) of up to ±80 V.