Zener diode and voltage regulation
Semiconductors · Physics
DC circuit
Interactive 3DElectrons drift around the loop — raise the voltage and watch the current obey Ohm's law.
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1V12V
Study notes
A 5.1 V, 0.5 W Zener regulates a load from a 9 V supply through R_S = 100 Ω. (a) Max Zener current rating? (b) With the load drawing 20 mA, find the Zener current and check safety. Solution: (a) I_Zmax = P/V = 0.5/5.1 ≈ 98 mA. (b) Total current through R_S: I = (9 − 5.1)/100 = 39 mA. Zener current I_Z = 39 − 20 = 19 mA < 98 mA — safe, with margin. If the load disconnects, I_Z = 39 mA — still safe.