DC-DC converters worksheet with answers

Free printable DC-DC converters worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
+−5 VD = 0.2LCR+−Vo​ = ?

An ideal buck converter runs from 5 V with a duty cycle D = 0.2 in continuous conduction. Find the output voltage Vo.

Vin​ = 5 VD = 0.2
Vo = V
2.Easy
+−12 VD = ?LCR−+8 V

An ideal inverting buck-boost converter must produce −8 V from 12 V in continuous conduction. Find the duty cycle D.

Vin​ = 12 VVo​ = −8 V
D =
3.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 48 V into 28.8 V for an 8 Ω load. It switches at 200 kHz with L = 220 µH. Find the peak inductor current Imax.

Vin​ = 48 VVo​ = 28.8 Vf = 200 kHzL = 220 µHR = 8 Ω
Imax = A
4.Medium
+−36 VSL = ?CR+−10.8 V

An ideal buck converter turns 36 V into 10.8 V at a switching frequency of 250 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 0.5 A.

Vin​ = 36 VVo​ = 10.8 Vf = 250 kHzΔIL = 0.5 A
L = µH
5.Hard
tiL​Imax​IL​DTT2T

An ideal inverting buck-boost converter turns 9 V into −27 V for a 25 Ω load at 250 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 9 VVo​ = −27 Vf = 250 kHzR = 25 Ω
Lcrit = µH
6.Hard
+−24 VSLC = 470 µFR = 25 Ω−+−36 V

An ideal buck-boost converter turns 24 V into −36 V for a 25 Ω load at 50 kHz. The output capacitor is 470 µF. Find the peak-to-peak output voltage ripple ΔVo in mV.

Vin​ = 24 VVo​ = −36 Vf = 50 kHzC = 470 µFR = 25 Ω
ΔVo = mV

Answer key

  1. 1. Vo = 1 V
  2. 2. D = 0.4
  3. 3. Imax = 3.731 A
  4. 4. L = 60.48 µH
  5. 5. Lcrit = 3.125 µH
  6. 6. ΔVo = 36.77 mV

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