• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 388 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ISO5452: Short-circuit protection

Patrick Zeng
Intellectual 1090 points
Part Number: ISO5452
Other Parts Discussed in Thread: ISO5852S

Hi team,

  My customer was using ACPL-337J for HVAC compressor projects and I think I've identified their current design challenge and would like to see if ISO5452 can solve it.

  Description:,

  Customer was using ACPL-337J to drive FF600R12IP4. The system OCP is set to be 1200A, desaturation current is set 2400A. The target is to keep VCE<1200V whenever short happens. ACPL-337J can only initiate soft turn-off after hitting desaturation current(2400A), which means the VCE may be above 1200V during current rising from 1200A to 2400A. In order to solve the problem, customer is using a big RES for shut-down. The efficiency get worse as a compromise.

  I notice that ISO5452 can initiate soft turn-off right after OCP(1200A), then enter Desat(2400A). It might help solve the problem.

  Can you double check with my assumption above? And if your team can provide more details or test data, it would be very helpful for me to engage customer.

 Thank you and looking forward to your reply..

Regards,

Patrick

 

  • 0
    TI__Expert 4875 points

    Hi Patrick,

    Thanks for your question.

    The DESAT voltage threshold is be set according to saturation voltage, V_CE(sat), of the IGBT at the short-circuit current. ISO5452 has a DESAT threshold of 9V which is common for short-circuit protection of IGBTs. The threshold can be adjusted if desired with external components. When the current of the IGBT rises such that V_CE(sat) reaches 9V, then the ISO5452 initiates the soft shutdown to prevent high voltage spikes during turn off. The waveforms corresponding to DESAT detection are in Figures 15-18 on page 15 of the DS. 

    You can set the threshold for either 1200A or 2400A. Typically, the DESAT threshold is set to the short-circuit current (2400A in your case) since this would be the region where the IGBT goes into desaturation. It is also possible to set the over-current detection to a lower current threshold, 1200A, as long as it is sufficiently higher than the operating current as to prevent false triggering.

    You could also look at the operation in TIDA-00195 starting on page 46. It shows the short circuit protection test results and operation of ISO5852S, which uses the same DESAT protection as ISO5452.

    I hope this answers your questions!

    Regards,

    Audrey