Dear all,
I had followed the datasheet steps to design the converter before the board cut, how to estimate the power losses between components?
Are there any spreadsheet can be compute the design constrain etc?
Thank you
ENJOY~
Hi Brian,
You may utilize the Application section of the device datasheet to size the parts, and calculate for power dissipation considerations. Page 21-24.
Best,
Nouman
Thank you for the suggestions.
But I am not sure some of the missing clues:
How to estimate the tr, tf?
Thank you
Hi Brian,
You may obtain the rise and fall time information of switch based on the FET you chose.
The tr and tf are parameters listed in the FET datasheets as turn-on rise time and turn-off fall time.
Please let me know if further clarification is needed.
Thank you,
Nouman
I am a bit confused by these parameters.
Do the equation is considering a targeted fsw and under that fsw the tr and tf is based on some targeted operation point?
Correct me if misunderstood, the MOSFET edge time is based on the gate drive delivery, Rgate Ctot etc.
And such tr / tf is not affected by fsw and duty cycle unless the tr / tf > t(duty cycle)+ tdead.
So datasheet tr/tf is based on a measured time on some gate drive parameter, but might not be applied to what MP2918 gate drive provied.
i.e. at 150khz the VOUT = VIN × D
tON/(tON + tOFF) = D
Then D is the duty cycle i.e. 5V/30V = 1/6 @ tperiod = 1/fsw=1/150khz=6.66us aka 1.111us
So the pos neg edge at tON is the high-side MOSFET and tOFF pos neg edge is the low-side MOSFET.
And dead time is inserted between the middle between these two on off state.
Thankyou
ENJOY~
Dear Nouman,
I think MPS do provide MPSmart which only include MP2908A.
But I guess both of these two devices are sharing the same Error-Amp designs and almost the same.
Correct me if wrong, I think we can use MP2908 as a starting point to design the converter.
Bests,
Brian
Hi Brian,
Can you please confirm as to why you are not going with converters that have fet integrated?
Regarding your message from last week, apologies, which specific FET are you looking into, possibly I can take a quick look.
Yes, MP2908A would be a good starting point to simulate.
Regards,
Nouman
No worry Nouman, the major reason is because the specification is not possible maybe from MPS.
we are targeting a >30V and buck 3.6V output and over 60W system.
From simulation we had selected a MOSFET of BSC034N06 x1 @ H&L side.
And inductor should be around 1uH @ Rsense of 3mR.
If possible please discuss via Email?
Thank you,
ENJOY~