Please check the Mos driver waveform of MP9928

DC-DC Power Converters
1

Hi, MPSer
Please help to check the Mos driver waveform of MP9928, the driver’s input voltage is 24V and output 12V/6A,now we tested component temprature isn’t balance,the upper side of Mos Q4 is higher than low one of Q5. we found their time of Ton is diffrent between two mosfet. please explain the pheanomeno and give some insturctions to find the cause,thanks

1.Two Mosfet’s driver waveform:

Test 6
Test 6800×600 21.2 KB

2

2.Schematic:

MP9928
MP99281175×439 144 KB

3
  1. We have a similar sample from customer and we test it ok.
    Test 7
    Test 7800×600 21.3 KB
4

Hello,

Try changing the BST circuitry to match the reference design.
image
Where BST node is only touching the R and the RCD share a node.

Regards,
Jonathan