One of my customers is evaluating TPS54240 for their new products.
They use parts parameters which calculated by TPS54240 Webench.
Their Vin/Vo/Io conditions are the follows.
Vin = 33.2V(Min), 36.9V(Nom), 40.6V(Max)
Vo = 3.3V
Io = 0A(Min) ~ 0.5A(Max)
Webench calculated the following values for compensation parts and output C and L with conditions above.
Ccomp = 100nF
Ccomp2 = 82pF
Rcomp = 5.36kohm
L1 = 82uH
Cout = 47uF
They used these parameter values for their evaluation. But they found that the output transient response response was very slow.
The output voltage dropped to 3.0V after 300us on their own board when output current was changed from 0A to 0.5A.
As the result of Webench load transient simulation (0.05A <-> 0.5A) with parameters above, the output voltage was dropped to 3.15V.
They have the following questions at this moment. Could you please give me your reply for them?
Q1. I want to reduce the output voltage dropping level at load current increasing (0A -> 500mA).
Could you please tell me how to achive that? For example, Is it Ccomp, Rcomp, Ccomp2 adjusting?
Or is it better to add small capacitor between Vo and VSENSE terminal?
Q2. In case of Ccomp, Rcomp, Ccomp2 adjusting, could you please tell me how to chose the best combination.
Is it webench transient response and bode plot simulation using with each parameter changing.
Q3. In case of TPS54240, is there big difference of load transient time between 0A -> 500mA condition and 50mA -> 500mA condition?
Your reply would be much appreciated.