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
+−48 VLD = 0.4CR+−Vo​ = ?

An ideal boost converter runs from 48 V with a duty cycle D = 0.4 in continuous conduction. Find the output voltage Vo.

Vin​ = 48 VD = 0.4
Vo = V
2.Easy
+−24 VD = ?LCR−+56 V

An ideal inverting buck-boost converter must produce −56 V from 24 V in continuous conduction. Find the duty cycle D.

Vin​ = 24 VVo​ = −56 V
D =
3.Medium
+−15 VSL = ?CR+−9 V

An ideal buck converter turns 15 V into 9 V at a switching frequency of 50 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 0.6 A.

Vin​ = 15 VVo​ = 9 Vf = 50 kHzΔIL = 0.6 A
L = µH
4.Medium
+−12 VLSCR = 15 Ω+−20 V

An ideal boost converter turns 12 V into 20 V for a 15 Ω load. Find the average inductor current IL.

Vin​ = 12 VVo​ = 20 VR = 15 Ω
IL = A
5.Hard
tiL​Imax​IL​DTT2T

An ideal buck converter turns 15 V into 4.5 V for a 50 Ω load at 200 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 15 VVo​ = 4.5 Vf = 200 kHzR = 50 Ω
Lcrit = µH
6.Hard
+−15 VSL = 68 µHC = ?R+−6 V

A buck converter turns 15 V into 6 V at 100 kHz with L = 68 µH. Find the output capacitance C that limits the peak-to-peak output ripple to 20 mV.

Vin​ = 15 VVo​ = 6 Vf = 100 kHzL = 68 µHΔVo = 20 mV
C = µF

Answer key

  1. 1. Vo = 80 V
  2. 2. D = 0.7
  3. 3. L = 120 µH
  4. 4. IL = 2.222 A
  5. 5. Lcrit = 87.5 µH
  6. 6. C = 33.09 µF

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