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 VD = ?LCR+−19.2 V

An ideal buck converter must produce 19.2 V from 48 V in continuous conduction. Find the duty cycle D.

Vin​ = 48 VVo​ = 19.2 V
D =
2.Easy
+−48 VSLCR+−24 V

An ideal buck converter turns 48 V into 24 V and delivers 1.5 A to its load. Find the average input current Iin.

Vin​ = 48 VVo​ = 24 VIo = 1.5 A
Iin = A
3.Medium
tiL​Imax​ = ?Imin​Io​DTT2T

A buck converter turns 48 V into 24 V for an 8 Ω load. It switches at 40 kHz with L = 330 µH. Find the peak inductor current Imax.

Vin​ = 48 VVo​ = 24 Vf = 40 kHzL = 330 µHR = 8 Ω
Imax = A
4.Medium
+−9 VSL = ?CR+−2.7 V

An ideal buck converter turns 9 V into 2.7 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​ = 9 VVo​ = 2.7 Vf = 250 kHzΔIL = 0.6 A
L = µH
5.Hard
tvo​Vo​ΔV = ?DTT2T

A buck converter turns 12 V into 3 V for a 12 Ω load at 200 kHz, with L = 220 µH and C = 22 µF. Find the peak-to-peak output voltage ripple ΔVo in mV.

Vin​ = 12 VVo​ = 3 Vf = 200 kHzL = 220 µHC = 22 µF
ΔVo = mV
6.Hard
tiL​Imax​IL​DTT2T

An ideal inverting buck-boost converter turns 9 V into −6 V for a 50 Ω load at 100 kHz. Find the smallest inductance Lcrit for continuous conduction.

Vin​ = 9 VVo​ = −6 Vf = 100 kHzR = 50 Ω
Lcrit = µH

Answer key

  1. 1. D = 0.4
  2. 2. Iin = 0.75 A
  3. 3. Imax = 3.455 A
  4. 4. L = 12.6 µH
  5. 5. ΔVo = 1.453 mV
  6. 6. Lcrit = 90 µH

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