Tool/software: WEBENCH® Design Tools
I have used the work bench to create work bench with inuts of
Vin min : 24V
Vin max : 30V
Vout ; 24V
Iout: 16A
I see two mosfets in parallel on the top part of the H bridge, why is there unequal distribution and can it be replaced by one big mosfet.
Hi Nidhi,
Normally we can observe the parallel fets for high current input cases. This is might be due to the single fet solution for that particular fet is not feasible as it might be hitting maximum junction temperature.
We can always select another fet solution through select alternate option. Please look for fet (M1,M2) quantity equal to 1 and select that solution. I went ahead and created one example work bench for your input case( below link). Hope this helps.
Work bench: https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=FC38F41C0871F167
How to choose alternate Fets:
Best Regards,
Bhushan
Hi Nidhi,
Could you please try out the workbench which I have shared below ? It has both pairs with quantity 1 mosfets.
Work bench with both pairs of single mosfet: https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=622BD3CBD349A766
As per my understanding you are referring to load transient simulations. This gives information on overshoot/undershoot if Iout is suddenly drops/ups between 16A and 1.6 A (for your input case).
Overshoot/ undershoot at Vout are mostly depend on
1. How much big the change in Iout we are expecting in our application ( for example design above Iout change is from 16A to 1.6A)
2. How big is our output capacitor ( the bigger cap --> lower the shoot)
3. How sudden is the change in load. (lesser the time more the shoot)
All the above points can be udpated in the Webench to meet transient requirements. If we are not expecting this much transient, please modify the above work bench as per your requirements. I would suggest you to check out steady state waveform as well.
Best Regards,
Bhushan
Hi Nidhi,
Currently the fet selection happens as a pair (for synchronous converter) and not as a single fet. The algorithm will check if mosfets as a pair works for the particular input case or not. For your case (LM5175), we will not be able select the fets separately.
But we can always look for alternate solutions as well. Please follow below steps. Hope this helps.
1. Click on below link.
https://webench.ti.com/power-designer/switching-regulator?powerSupply=
2. Add your inputs (Vin, Vout, Iout) and click on view designs. Webench should give you possible list of solutions
Best Regards,
Bhushan
