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 VSLCR−+15 V

An ideal buck-boost converter turns 5 V into 15 V and delivers 2.5 A to its load. Find the average input current Iin.

Vin​ = 5 VVo​ = 15 VIo = 2.5 A
Iin = A
2.Easy
+−36 VLD = ?CR+−90 V

An ideal boost converter must produce 90 V from 36 V in continuous conduction. Find the duty cycle D.

Vin​ = 36 VVo​ = 90 V
D =
3.Medium
+−36 VSL = ?CR+−10.8 V

An ideal buck converter turns 36 V into 10.8 V at a switching frequency of 250 kHz. Find the inductance L that keeps the peak-to-peak inductor ripple current at 0.6 A.

Vin​ = 36 VVo​ = 10.8 Vf = 250 kHzΔIL = 0.6 A
L = µH
4.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 9 V into 4.5 V for a 2.5 Ω load. It switches at 100 kHz with L = 33 µH. Find the peak inductor current Imax.

Vin​ = 9 VVo​ = 4.5 Vf = 100 kHzL = 33 µHR = 2.5 Ω
Imax = A
5.Hard
tiL​Imax​Io​DTT2T

A buck converter turns 36 V into 18 V at 50 kHz with L = 150 µH. Find the smallest load current Io,min for which it stays in continuous conduction.

Vin​ = 36 VVo​ = 18 Vf = 50 kHzL = 150 µH
Io,min = A
6.Hard
tiL​Imax​IL​DTT2T

An ideal buck converter turns 12 V into 6 V for a 4 Ω load at 100 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 12 VVo​ = 6 Vf = 100 kHzR = 4 Ω
Lcrit = µH

Answer key

  1. 1. Iin = 7.5 A
  2. 2. D = 0.6
  3. 3. L = 50.4 µH
  4. 4. Imax = 2.141 A
  5. 5. Io,min = 0.6 A
  6. 6. Lcrit = 10 µH

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