TVS1801: Broken in short mode.

Hi Ryu,

what was the impedance at the output of the surge generator? This will determine the peak current flow which may have violated the AB’s max of the device.

Regards,

Sebastian 

Hi Sebastian,

Thanks for the reply.
The output impedance of the surge generator is 2Ω.

Regards,
Ryu.

Hi Ryu,

A surge event with a 0.4kV open circuit voltage and a 2 Ohm output impedance at the surge generator would have a peak current of 200 A. 400V/2Ω= 200A.

Our app note Demystifying surge protection goes into further details. 

This would violate the TVS1801 peak surge current rating of 30A for the 8/20us waveform.

What is the application here?

Depending on the application, the output impedance of the surge generator could be higher which would result in lower peak currents. 

Regards,

Sebastian 

Hi Sebastian,

Thanks for the reply.
Does this mean that TVS1801 is set at 42 ohm standard since it is a device for signal lines?
Therefore, it was not originally designed to be tested at 2 ohms?

Regards,
Ryu.

Hi Ryu,

Your understanding is correct, the TVS1801 was designed for data line surge protection where the impedance at the output of the surge generator would be 42Ohms. Is this being used for data or power line protection? 

It was not designed to be tested at 2 Ohm, it would only be able to handle ~30A of peak surge current. So it could only withstand an open circuit voltage of about 60V through a 2Ohm network. 

Regards,

Sebastian