Hi,
I would like to ask you about the UCC28950 device.
I am selecting Db and Dc for the clamp diode.
The data sheet mentions Equation 66. What loss does this equation show? Is the diode forward loss?
I calculated according to the contents of the data sheet, but this loss is about 12W. (Ls = 26uH, Iprms = 3.1A, Fsw = 100kHz)
Can the MURS360 diode in the datasheet tolerate this loss? Or is my calculation method different?
Best regards,
Is it possible to answer my question?
Other formulas in the data sheet have calculated the resulting values, but Equation 66 does not show the resulting values.
Also, looking at the MURS360 data sheet, the following figure is shown.
When DC3A flows, about 3W loss occurs.
According to my calculation, the result of Equation 66 is 12W, but I think that the loss of 12W is too much for MURS360.
Best regards,
Hello Kaji
My apologies for the added delay - I had hoped to be able to get an analytical answer for you but I was not able to find one nor did I have time to develop one. What I did do is to run a simulation in TINA-TI and I got the following waveforms. You can see that the peak current int he diode is approximately 545mA and that it decays away to 0 over a time of 1us. You can calculate the dissipation in the diode from the average current (0.5*545mA*1us/10us) times the Vf (0.7V - assumed) . It comes out to be about 20mW.
The third trace is the input current into the H bridge - the peak is 2.9A. You can see that the peak diode current is only about 20% of the peak input current.
My advice would be for you to download the TINA sim and use it to model your own system. You can find the simulation at https://www.ti.com/lit/tsc/slum276
I added current meters into the diode and input circuits as shown here - you will need to do the same -
Hopefully this gives you enough information to continue to work.
