Part Number:TPS65400
Tool/software: WEBENCH® Design Tools
I am designing using TPS65400, to make question easier lets focus on SW3 .
My parameters are Vin=5V, Vout =1.8V, Iout 1.8A, Cout =2x 10uF 1mohm ESR
From webench I am getting Rfb1=20k, RfB2=16k, Rcomp=9.09kohm, Ccomp=1.8nF, Ccomp2=39pF
Using eqation for Rc from data sheet page 24 Table 3 Rc=(2*pi*fc*Co*V0)/(Gm*Gmps*Vref), and assuming as data sheet says Gm=120uA/V, Gmps=10A/V and Vref =0.8V I am getting Rc=27kOhm while webench calculates 9.090kOhm.
Then of cource since Rc is wrong all othe calculations ( Cc and Croll) are wrong.
But even assuming Rc=9090ohm, acc to same data sheet Cc=(Rl*Co)/Rc= (1*0.00002)/9090=2.2nF not 1.8nF given by webench?
Also Cc2=Croll=(Resr*Co)/Rc=(0.0005*0.00002)/9090=1.1pF not 39pF given by webench?
Could you please explain the discrapencies and advise what equations should be used for calculations.
Also is there a chance to run simulations (especially bode plot) in webench for TPS65400 , I can not find options to run them in the menu?
Thanks Sebastian
Since Rc i sused in all othe requations all ot