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TVS1401: Interface forum

Part Number: TVS1401

Hi Andy,

My customer need to know the factor of Steady "State Power Dissipation" which is not shown in the datasheet. Could you please kindly advise it?

Thanks a lot.

Vincent Chen

  • Hi Vincent,

    Welcome to E2E!

    I'm not entirely sure I understand what the customer is looking for. All the data and information we have of the TVS1401 is what is provided in the datasheet. During steady state the TVS1401 device should be essentially invisible to the system and will only conduct in the presence of surge transients for which the device has a power rating of 600W per the IEC 61000-4-5 surge test and 120W per IEC 61643-321 test. Could you elaborate on the concern the customer has regarding the power dissipation of the device?

    Best regards,

    Andy Robles

  • Hi Andy,

    Please find below protection circuit, we proposed TVS1401 for not only surge protection but can withstand continuous +/-30V EOS test. Therefore, the power dissipation is accumulated on TVS part that is why we need to know the parameter of State Power Dissipation to check if any risk to burn out TVS part.

    Thanks a lot.

    Vincent Chen

  • Hi Vincent,

    The TVS1401 device is only tested per the IEC 61000-4-x test which you can get more details on in the application report IEC 61000-4-x Tests for TI’s Protection Devices.

    The tests described in that document are transients which is what the device is designed to handle. The device is not designed to handle continuous voltages that exceed the pulse duration of the tests it is rated against which the longest test is the IEC 61000-4-5 surge/lighting test. The current going through the device will end up damaging the TVS1401 if it is exposed to higher voltages for longer periods of the time.

    By continuous +/-30V EOS do you mean constant DC voltage?

    Best regards,

    Andy Robles

  • Hi Andy,

    Yes, continuous +/-30V EOS is constant DC voltage test. In the protection shown above, the RP1 is 590ohm, R1 is 3.4Kohm. The TVS1401's min. clamp voltage is 17.1V and ADC will clamp voltage at about 5.3V. Then the calculated breakdown current through TVS1401 is about 20mA. The power dissipate on TVS1401 is 17.1Vx20mA=342mW. 

    So, I would like to know TVS1401 can withstand 342mW dissipation continuously?

    Thanks a lot.

    Vincent Chen

  • Hi Vincent,

    Although the device does have a min breakdown voltage spec of about 17.1V if higher voltages are applied the current through the device will increase exponentially and will blow up the device.

    I apologize, not sure if I'm missing something, but how exactly are you calculating the 20mA? Will the TV1401 be limited to these 20mA? In the datasheet we do spec the max DC current the device can withstand at 45mA.

    Best regards,

    Andy Robles

  • Hi Andy,

    Applying 30V at terminal block then current flow through RP1(590ohm) to TVS diode which will clamp voltage to about 17.1V. The current will be limited by RP1 and below is how I calculate it. Do you think it makes sense?

    (30V-17.1V)/590ohm is about 20mA. 

    As you mentioned TVS1401 can withstand max. DC current up to 45mA, can I say this kind of scenario will not damage TVS diode due to the DC  current is only 20mA? 

    Thanks very much.

    Vincent Chen

  • Hi Vincent,

    I see what you mean now. The RP1 resistor would in fact limit the current which if it stays below the max DC current of 45mA the device will be able to withstand the test. I haven't encountered a configuration or a test like this before so even though it works in theory, the system will have to be tested by the customer to ensure the devices functionality.

    Best regards,

    Andy Robles

  • Hi Andy,

    Understood, thanks a lot for your comment.

    Vincent Chen