• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 184 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

UCC21530: INA/INB Input Filter Design

Brian Wang0928
Genius 11650 points
Part Number: UCC21530

Since customer is suffering the output damaged of the UCC21530 issue during surge test (Worse case with 6KV at LINE to Nature), they modified the C_filter from 100pF to 1nF with R_filter=100R and increasing the dead-time a little from 1.2uS to 1.5uS(Working freq=20KHz). The damage issue is gone so far. However, customer wondering to know if these filter values are optimized and meet device's requirement or not? On the d/s, the recommended input filter cap is in range of the 10pF to 100pF. Is there any problem with 1nF?  

application: 3 Level DC-AC Solar Inverter

Regards

Brian W

  • 0
    TI__Expert 4070 points

    Hi Brian,

    Thanks for reaching out!

    Regarding the RC filter as you mentioned, the C_in is larger than the datasheet recommends (with R_in still at 100 Ohm).

    Regarding consequences of the RC time constant being larger, there will be a longer propagation delay, and there may be some unwanted shaping of the input waveform.  This is also contingent on the input waveform voltage.

    If there is excessive shaping of the input waveform (from the RC filter), this may also affect when the input voltage threshold is reached.

    I hope this answers your question, otherwise feel free to follow up!

    Thanks,

    Aaron Grgurich