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Original question:

UCC24612: False SR turn-on due to DCM ringing

UCC24612: UCC24612 used to boost SR mosfet driver

Vincent Li00
Intellectual 2035 points
Part Number: UCC24612

Hi Guys

our customer wants to use UCC24612 to drive boost high side FET. Here we just change the boost Diode to MOSFET to decrease the power loss at Rdson. 

48Vin - 80Vout/ 20A; So do we have some this application experience? In my opinion, two points need to concern:

1, The VCC voltage, UCC24612 only support 24V, For 80V system, we need to a isolated power supply in our voltage range;

2. For TM mode, because the current could go to 0  by itself. we don't mind it. But for CCM mode, could UCC24614 turn off by itself? So UCC24612 can turn off at no reverse current condition, right? or it just need a VDS voltage to turn on and turn off? VDS>threshold, turn on. and the VDS<threshold, turn off?

If it can turn off by itself, will  the 20A reverse current have some chanllenge for our device? No reverse current issue here?

Thanks

-Pengfei

  • 0
    TI__Guru 73355 points
    1. No we have not used UCC24612 in such applications. Please draw a draft circuit and we can help to review and provide our comment.
    2. UCC24612 can be used in CCM with switching frequency not exceeding 100kHz. otherwise, its associated switching losses will be too high.
  • 0 in reply to Hong Huang
    TI__Intellectual 2035 points
    So here except high switching losses at 100kHz, any other risk? My concern: here the current will be about 20A, there will be very high reverse recovery current, right? So our UCC24612 can handle this level current to turn off effectively？
    thanks
    -Pengfei
  • 0 in reply to Vincent Li00
    TI__Guru 73355 points
    UCC24612 will work to turn off as it is specified. To handle 20A, proper MOSFET(s) need to be decided then need to decide if UCC24612 has enough capability to drive the MOSFETs. There will be associated losses, but with fsw < 100kHz, the losses should be in reasonable range to our understanding. But in a particular design case and applications, it is needed to estimate if ok to accept that much power losses or a lower fsw is acceptable.