The TBU ® device, constructed using MOSFET semiconductor
technology, placed in the system circuit will monitor the
current with the MOSFET detection circuit triggering to provide
an effective barrier behind which sensitive electronics are not
exposed to large voltages or currents during surge events. The
TBU ® device operates in approximately 1 μs - once line
current exceeds the TBU ® device’s trigger current Itrigger.
When operated, the TBU ® device restricts line current to less
than 1 mA typically. When operated, the TBU ® device will
block all 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 V reset level. The TBU ®
device will automatically reset on lines which have no DC bias
or have DC bias below V reset (such as unpowered signal lines).
If the line has a normal DC bias above V reset , the voltage
across the TBU ® device may not fall below V reset after the
surge. In such cases, special care needs to be taken to ensure
that the TBU ® device will reset, with software monitoring as one
method used to accomplish this. Bourns application
engineers can provide further assistance