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
+−12 VLSCR+−48 V

An ideal boost converter turns 12 V into 48 V and delivers 2 A to its load. Find the average input current Iin.

Vin​ = 12 VVo​ = 48 VIo = 2 A
Iin = A
2.Easy
+−12 VSLCR+−4.8 V

An ideal buck converter turns 12 V into 4.8 V and delivers 3 A to its load. Find the average input current Iin.

Vin​ = 12 VVo​ = 4.8 VIo = 3 A
Iin = A
3.Medium
tiL​Imax​Imin​ΔI = ?DTT2T

An ideal inverting buck-boost converter turns 15 V into −22.5 V at 100 kHz with L = 68 µH. Find the peak-to-peak inductor ripple current ΔIL.

Vin​ = 15 VVo​ = −22.5 Vf = 100 kHzL = 68 µH
ΔIL = A
4.Medium
tiL​Imax​Imin​ΔI = ?DTT2T

An ideal inverting buck-boost converter turns 12 V into −36 V at 20 kHz with L = 150 µH. Find the peak-to-peak inductor ripple current ΔIL.

Vin​ = 12 VVo​ = −36 Vf = 20 kHzL = 150 µH
ΔIL = A
5.Hard
+−24 VSL = 68 µHC = ?R+−18 V

A buck converter turns 24 V into 18 V at 40 kHz with L = 68 µH. Find the output capacitance C that limits the peak-to-peak output ripple to 25 mV.

Vin​ = 24 VVo​ = 18 Vf = 40 kHzL = 68 µHΔVo = 25 mV
C = µF
6.Hard
tiL​Imax​IL​DTT2T

An ideal inverting buck-boost converter turns 48 V into −144 V for a 20 Ω load at 200 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 48 VVo​ = −144 Vf = 200 kHzR = 20 Ω
Lcrit = µH

Answer key

  1. 1. Iin = 8 A
  2. 2. Iin = 1.2 A
  3. 3. ΔIL = 1.324 A
  4. 4. ΔIL = 3 A
  5. 5. C = 206.8 µF
  6. 6. Lcrit = 3.125 µH

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