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 VD = ?LCR+−21.6 V

An ideal buck converter must produce 21.6 V from 48 V in continuous conduction. Find the duty cycle D.

Vin​ = 48 VVo​ = 21.6 V
D =
2.Easy
+−15 VLD = ?CR+−37.5 V

An ideal boost converter must produce 37.5 V from 15 V in continuous conduction. Find the duty cycle D.

Vin​ = 15 VVo​ = 37.5 V
D =
3.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 15 V into 10.5 V for a 2 Ω load. It switches at 40 kHz with L = 68 µH. Find the peak inductor current Imax.

Vin​ = 15 VVo​ = 10.5 Vf = 40 kHzL = 68 µHR = 2 Ω
Imax = A
4.Medium
+−15 VSL = ?CR+−7.5 V

An ideal buck converter turns 15 V into 7.5 V at a switching frequency of 500 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 0.3 A.

Vin​ = 15 VVo​ = 7.5 Vf = 500 kHzΔIL = 0.3 A
L = µH
5.Hard
tiL​Imax​Io​DTT2T

A buck converter turns 36 V into 10.8 V at 20 kHz with L = 47 µH. Find the smallest load current Io,min for which it stays in continuous conduction.

Vin​ = 36 VVo​ = 10.8 Vf = 20 kHzL = 47 µH
Io,min = A
6.Hard
+−12 VLSC = 100 µFR = 20 Ω+−40 V

An ideal boost converter turns 12 V into 40 V for a 20 Ω load at 50 kHz. The output capacitor is 100 µF. Find the peak-to-peak output voltage ripple ΔVo in mV.

Vin​ = 12 VVo​ = 40 Vf = 50 kHzC = 100 µFR = 20 Ω
ΔVo = mV

Answer key

  1. 1. D = 0.45
  2. 2. D = 0.6
  3. 3. Imax = 5.829 A
  4. 4. L = 25 µH
  5. 5. Io,min = 4.021 A
  6. 6. ΔVo = 280 mV

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