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.
Hi Team,
The reference design in the customer's UCC28950 specification. The board only supplies the chip (UCC28950 and UCC27324) with 12V voltage, and the mos tube has not yet supplied high voltage, but UCC27324 is very hot. Could it be caused by the drive transformer? Turn ratio 50:50:50
Regards,
Annie Liu
Hi Annie,
This sounds like it could be a magnetizing current issue. Here are a few things to check:
This device uses a hybrid pullup with a very small PMOS. Therefore it has a fairly large impedance when the output is high, as the PMOS has to source all of the current:
So you can use I^2*R with this value and the rms magnetizing current to estimate power dissipation. If you use the newest generation version of this device (UCC27624), it will have about 1/6 the resistance for pullup, and therefore less power dissipation.
Also, I can help calculate power losses more accurately if you can include more of the secondary side.