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 VSLCR+−12 V

An ideal buck converter turns 48 V into 12 V and delivers 1.5 A to its load. Find the average input current Iin.

Vin​ = 48 VVo​ = 12 VIo = 1.5 A
Iin = A
2.Easy
+−5 VLD = ?CR+−20 V

An ideal boost converter must produce 20 V from 5 V in continuous conduction. Find the duty cycle D.

Vin​ = 5 VVo​ = 20 V
D =
3.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 24 V into 12 V for a 12 Ω load. It switches at 250 kHz with L = 100 µH. Find the peak inductor current Imax.

Vin​ = 24 VVo​ = 12 Vf = 250 kHzL = 100 µHR = 12 Ω
Imax = A
4.Medium
+−15 VLSCR = 20 Ω+−37.5 V

An ideal boost converter turns 15 V into 37.5 V for a 20 Ω load. Find the average inductor current IL.

Vin​ = 15 VVo​ = 37.5 VR = 20 Ω
IL = A
5.Hard
tiL​Imax​IL​DTT2T

An ideal inverting buck-boost converter turns 9 V into −13.5 V for a 4 Ω load at 50 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 9 VVo​ = −13.5 Vf = 50 kHzR = 4 Ω
Lcrit = µH
6.Hard
+−48 VSL = 33 µHC = ?R+−33.6 V

A buck converter turns 48 V into 33.6 V at 100 kHz with L = 33 µH. Find the output capacitance C that limits the peak-to-peak output ripple to 100 mV.

Vin​ = 48 VVo​ = 33.6 Vf = 100 kHzL = 33 µHΔVo = 100 mV
C = µF

Answer key

  1. 1. Iin = 0.375 A
  2. 2. D = 0.75
  3. 3. Imax = 1.12 A
  4. 4. IL = 4.688 A
  5. 5. Lcrit = 6.4 µH
  6. 6. C = 38.18 µF

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