I have the below buck converter..
Now I'm trying to figure out how quickly or slowly I should soft start it. The only way I could think of doing it is to see how long it would take to charge the capacitor with my "excess" current. At full blast my load will require 3.5Amps and my power supply can supply 4.5Amps giving me 1Amp to use in charging the capacitor. Total charge Qon fully charged capacitor = C*V = 1.8e-3 * 24 = .0432 Coulombs. Q= I * t, t= Q / I, so t= .0432 / 1 = 0.0432 seconds So I was thinking of ramping up to 100% duty linearly over that 43 milliseconds ie. about 2%/ms.
Is there a better way to calculate soft start time for my application?
Info not in schematic, power supply is rated at 24V 4.5A, tiger power model SYM04-3 (btw, I'm still looking for more information or datasheet on this if anyone knows where), FET is rated at 16A continuous, inductor at 8 Arms and capacitor at 3.7Amps ripple. The load is resistive (a peltier cooler) with an R of around 6.9 Ohms. Switching frequency not yet set, could use some recommendations.
Edward