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
+−9 VD = ?LCR−+13.5 V

An ideal inverting buck-boost converter must produce −13.5 V from 9 V in continuous conduction. Find the duty cycle D.

Vin​ = 9 VVo​ = −13.5 V
D =
2.Easy
+−36 VSLCR+−21.6 V

An ideal buck converter turns 36 V into 21.6 V and delivers 2 A to its load. Find the average input current Iin.

Vin​ = 36 VVo​ = 21.6 VIo = 2 A
Iin = A
3.Medium
+−24 VSL = ?CR+−14.4 V

An ideal buck converter turns 24 V into 14.4 V at a switching frequency of 250 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 2 A.

Vin​ = 24 VVo​ = 14.4 Vf = 250 kHzΔIL = 2 A
L = µH
4.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 15 V into 7.5 V for an 8 Ω load. It switches at 20 kHz with L = 150 µH. Find the peak inductor current Imax.

Vin​ = 15 VVo​ = 7.5 Vf = 20 kHzL = 150 µHR = 8 Ω
Imax = A
5.Hard
tiL​Imax​IL​DTT2T

An ideal buck converter turns 9 V into 2.7 V for a 25 Ω load at 50 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 9 VVo​ = 2.7 Vf = 50 kHzR = 25 Ω
Lcrit = µH
6.Hard
+−36 VLSC = 220 µFR = 25 Ω+−72 V

An ideal boost converter turns 36 V into 72 V for a 25 Ω load at 50 kHz. The output capacitor is 220 µF. Find the peak-to-peak output voltage ripple ΔVo in mV.

Vin​ = 36 VVo​ = 72 Vf = 50 kHzC = 220 µFR = 25 Ω
ΔVo = mV

Answer key

  1. 1. D = 0.6
  2. 2. Iin = 1.2 A
  3. 3. L = 11.52 µH
  4. 4. Imax = 1.563 A
  5. 5. Lcrit = 175 µH
  6. 6. ΔVo = 130.9 mV

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