Buck Converter

Question 1

Buck Converter Duty Cycle formula:

Answer 1

D = Vout / Vin

Question 2

Buck Converter Ripple Current formula:

Answer 2

ΔI_L = ((Vin - Vout) ⋅ D) / (fsw ⋅ L)

Question 3

Buck Converter Output Capacitor:

Answer 3

Cout = ΔI_L / (8 ⋅ Fsw ⋅ ΔVout)

Question 4

Buck Converter Ripple voltage across output capacitor (Cout):

Answer 4

∆Vcout = ∆Q / Cout = ∆I_L / (8 ⋅ fsw ⋅ Cout)

Question 5

difference in charge stored in Buck Converter capacitor:

Answer 5

1/2 ⋅ (ΔI_L/2) ⋅ (T/2) = ΔI_L / (8 ⋅ fsw)

Question 6

Buck converter load resistor when at the boundary between CCM and DCM:

Answer 6

(Iout = ΔI_L / 2 ), so: Rout = Vout / Iout

Question 7

Coil conduction losses (Buck Converter):

Answer 7

P_L1 = DCR ⋅ (I_L1,RMS)²

Question 8

Triangle with amplitude A / Sawtooth with amplitude A formula:

Answer 8

A / √3

Question 9

I RMS formula:

Answer 9

√((I_DC)² + (I_AC)²)

√((I_OUT)² + ((ΔI_L /2)/√3)²)

I_DC = I_OUT , I_AC = ΔI_L /2 during the whole period