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 = 0.3LCR+−Vo​ = ?

An ideal buck converter runs from 5 V with a duty cycle D = 0.3 in continuous conduction. Find the output voltage Vo.

Vin​ = 5 VD = 0.3
Vo = V
2.Easy
+−12 VLD = ?CR+−48 V

An ideal boost converter must produce 48 V from 12 V in continuous conduction. Find the duty cycle D.

Vin​ = 12 VVo​ = 48 V
D =
3.Medium
+−48 VSL = ?CR+−14.4 V

An ideal buck converter turns 48 V into 14.4 V at a switching frequency of 50 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 0.3 A.

Vin​ = 48 VVo​ = 14.4 Vf = 50 kHzΔIL = 0.3 A
L = µH
4.Medium
+−12 VLSCR = 25 Ω+−48 V

An ideal boost converter turns 12 V into 48 V for a 25 Ω load. Find the average inductor current IL.

Vin​ = 12 VVo​ = 48 VR = 25 Ω
IL = A
5.Hard
tiL​Imax​Io​DTT2T

A buck converter turns 36 V into 14.4 V at 20 kHz with L = 68 µH. Find the smallest load current Io,min for which it stays in continuous conduction.

Vin​ = 36 VVo​ = 14.4 Vf = 20 kHzL = 68 µH
Io,min = A
6.Hard
+−12 VSLC = 100 µFR = 50 Ω−+−36 V

An ideal buck-boost converter turns 12 V into −36 V for a 50 Ω load at 100 kHz. The output capacitor is 100 µF. Find the peak-to-peak output voltage ripple ΔVo in mV.

Vin​ = 12 VVo​ = −36 Vf = 100 kHzC = 100 µFR = 50 Ω
ΔVo = mV

Answer key

  1. 1. Vo = 1.5 V
  2. 2. D = 0.75
  3. 3. L = 672 µH
  4. 4. IL = 7.68 A
  5. 5. Io,min = 3.176 A
  6. 6. ΔVo = 54 mV

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