Switching losses at 500kHz obviously...your gate charge values are huge. For a 24V to 3.3V conversion, the Rdson can be higher (given the low duty cycle), resulting in lower Qg. Choose a 40V FET such as the CSD18504Q5A. Qg at Vgs = 5V is 8nC and Qgd/Qgs…
Hello,
Please use the FETPWRCALC buck converter NexFET selection tool to find suitable MOSFETs.
Also, please download and complete the LM5146DESIGN-CALC to assist with component selection and loss calculations
Regards,
Tim
Hi Ravid,
For this design, you've chosen one of our lowest rds(on) and highest gate charge FETs for both high side and low side. While this will minimize the conduction losses, it also increases the switching losses in the high side FET and gate drive…
Michael,
Thanks for posting.
The losses are simply for the CSD87350Q5D, they are not total system loss.
We do have some materials on power loss that you may find useful.
We have an online tool ( www.ti.com/.../fetpwrcalc ) that you can very quickly…
Harish,
Yes you are correct that varying frequency will impact your switching losses linearly.
Normally though is is charge and not capacitances that are used in the power loss equations our team uses.
For instance in th eapplication note here there…
Hi Florian,
Jut following up on this thread. Were you able to resolve the issue with a lower gate threshold MOSFET?
The Miller plateau is effectively the gate voltage at which the drain voltage transitions during switching, and the steady-state gate…
Bogey,
In theory yes, but I would be cautioned that the TI power block only has 25V BVDSS so depending on your input voltage and the amount of ringing you anticipate, you may want to use a 30V device/power block like the Fairchild dual-FET.
You may…
Where do you measure the efficiency? For the datasheet, the input/output voltage were measured on the input/output sense resistor. So, it doesn't include the ACFET loss, BATFET loss and input cable or trace loss because customer can change the ACFET and…
Part Number: CSD17510Q5A Hi expert,
I'm using your power loss calculation tool on http://www.ti.com/tool/fetpwrcalc .
But I cannot change low side MOSFET setting even I change low side FET to CSD17552.
If I need to calculate two MOSFET parallel condition…
Robert,
This sounds like a great application for power block! Power block datasheets are written more from a system level solution, as opposed to discreet FETs , so it just depends on your input conditions and how much power loss you are willing to accept…