2-13. An alternative circuit for energizing an inductor and removing the stored
energy without damaging a transistor is shown in Fig. P2-13. Here VCC 12 V,
L 75 mH, and the zener breakdown voltage is VZ 20 V. The transistor
switch opens and closes periodically with ton 20 ms and toff 50 ms.
(a) Explain how the zener diode allows the switch to open. (b) Determine and
sketch the inductor current i
L(t) and the zener diode current iZ(t) for one
switching period. (c) Sketch (p)(t) for the inductor and the zener diode.
(d) Determine the average power absorbed by the inductor and by the
zener diode