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
+−12 VD = ?LCR+−2.4 V

An ideal buck converter must produce 2.4 V from 12 V in continuous conduction. Find the duty cycle D.

Vin​ = 12 VVo​ = 2.4 V
D =
2.Easy
+−48 VD = 0.2LCR+−Vo​ = ?

An ideal buck converter runs from 48 V with a duty cycle D = 0.2 in continuous conduction. Find the output voltage Vo.

Vin​ = 48 VD = 0.2
Vo = V
3.Medium
tiL​Imax​Imin​ΔI = ?DTT2T

An ideal buck converter turns 15 V into 7.5 V at 50 kHz with L = 33 µH. Find the peak-to-peak inductor ripple current ΔIL.

Vin​ = 15 VVo​ = 7.5 Vf = 50 kHzL = 33 µH
ΔIL = A
4.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 12 V into 8.4 V for a 20 Ω load. It switches at 40 kHz with L = 220 µH. Find the peak inductor current Imax.

Vin​ = 12 VVo​ = 8.4 Vf = 40 kHzL = 220 µHR = 20 Ω
Imax = A
5.Hard
+−12 VSL = 150 µHC = ?R+−4.8 V

A buck converter turns 12 V into 4.8 V at 50 kHz with L = 150 µH. Find the output capacitance C that limits the peak-to-peak output ripple to 100 mV.

Vin​ = 12 VVo​ = 4.8 Vf = 50 kHzL = 150 µHΔVo = 100 mV
C = µF
6.Hard
tiL​Imax​IL​DTT2T

An ideal buck converter turns 36 V into 25.2 V for a 4 Ω load at 40 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 36 VVo​ = 25.2 Vf = 40 kHzR = 4 Ω
Lcrit = µH

Answer key

  1. 1. D = 0.2
  2. 2. Vo = 9.6 V
  3. 3. ΔIL = 2.273 A
  4. 4. Imax = 0.5632 A
  5. 5. C = 9.6 µF
  6. 6. Lcrit = 15 µH

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