• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 348 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.

LM5021: about vertical current limit stop

ACGUY
Guru 11170 points
Part Number: LM5021
Other Parts Discussed in Thread: TIDA-010000, UCC28740

Hi,

Does LM5021 have vertical current limit stop?

And, our customer has plan to design isolated dc/dc. That input in DC400V - DC1000V, output power is 10W.

They found the TIDA-010000, however this design has current buffer. They are conserned about switching delay and power loss at turn.

Could you let us know information for ideal TI's solution?

Regards,

ACGUY

 

  • 0
    TI__Expert 8210 points
    Hi

    LM5021 has cycle by cycle protection thru the current sense pin CS. If the voltage on this pin exceeds 0.5V the gate drive OUT pin is driven low.

    TIDA-010000 uses UCC28740 for the flyback controller rather than LM5021. It also has cycle by cycle protection on the CS pin. There is no "buffer" on this pin that prevents overcurrent protection.

    R21 provides the feed-forward line compensation to eliminate changes in IPP with input voltage due to the propagation delay of the internal comparator and MOSFET turnoff time. More information is in the UCC28740 datasheet. C22 is a filter capacitor to eliminate switching noise to prevent improper operation. it will create a low pass RC filter with R21 that will delay overcurrent protection by a bit, but the power stage can be designed to accommodate for this.

    Best Regards,
    Eric