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
+−15 VSLCR−+15 V

An ideal buck-boost converter turns 15 V into 15 V and delivers 1 A to its load. Find the average input current Iin.

Vin​ = 15 VVo​ = 15 VIo = 1 A
Iin = A
2.Easy
+−15 VLD = ?CR+−20 V

An ideal boost converter must produce 20 V from 15 V in continuous conduction. Find the duty cycle D.

Vin​ = 15 VVo​ = 20 V
D =
3.Medium
+−12 VSL = ?CR+−3 V

An ideal buck converter turns 12 V into 3 V at a switching frequency of 25 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 2 A.

Vin​ = 12 VVo​ = 3 Vf = 25 kHzΔIL = 2 A
L = µH
4.Medium
+−48 VSL = ?CR+−19.2 V

An ideal buck converter turns 48 V into 19.2 V at a switching frequency of 500 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 0.8 A.

Vin​ = 48 VVo​ = 19.2 Vf = 500 kHzΔIL = 0.8 A
L = µH
5.Hard
+−9 VSLC = 220 µFR = 20 Ω−+−21 V

An ideal buck-boost converter turns 9 V into −21 V for a 20 Ω load at 25 kHz. The output capacitor is 220 µF. Find the peak-to-peak output voltage ripple ΔVo in mV.

Vin​ = 9 VVo​ = −21 Vf = 25 kHzC = 220 µFR = 20 Ω
ΔVo = mV
6.Hard
tiL​Imax​IL​DTT2T

An ideal boost converter turns 15 V into 50 V for a 50 Ω load at 40 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 15 VVo​ = 50 Vf = 40 kHzR = 50 Ω
Lcrit = µH

Answer key

  1. 1. Iin = 1 A
  2. 2. D = 0.25
  3. 3. L = 45 µH
  4. 4. L = 28.8 µH
  5. 5. ΔVo = 133.6 mV
  6. 6. Lcrit = 39.38 µH

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