Digi-Key – Low-capacitance high-speed surge protection from stock (TBU-CA)

Now in stock and available for same-day despatch from Digi-Key, the Bourns TBU is a silicon-based, solid-state, resettable device that is placed in series with a signal path. The TBU (transient blocking unit) device operates in approximately 1μs once line current exceeds the TBU device’s trigger current. When operated, the TBU device typically restricts line current to less than 1mA. When operated, the TBU device will block all system voltages and any other voltages including the surge up to rated limits.

After the surge, the TBU device resets when the voltage across the TBU device falls to the Vreset level. The TBU device will automatically reset on lines that have no DC bias or that have a DC bias below Vreset (such as un-powered signal lines). If the line has a normal DC bias above Vreset, the voltage across the TBU device may not fall below Vreset after the surge. In such cases, special care needs to be taken to ensure that the TBU device will reset, otherwise an automatic or manual power down will be required, says the company.