• summary_type: application
• word_count: 160

A Zener diode operates in reverse breakdown where V_Z remains nearly constant despite varying current. Circuit: input V_in through series resistor R_s, Zener in reverse bias, load R_L in parallel with Zener. Operation: V_out = V_Z (constant) as long as I_Z > 0. Series current: I_s = (V_in - V_Z)/R_s. Load current: I_L = V_Z/R_L. Zener current: I_Z = I_s - I_L. Regulation holds when I_Z remains positive. Maximum load current: I_L_max = I_s (when I_Z = 0), giving R_L_min = V_Z/I_s. For varying V_in: the Zener absorbs voltage fluctuations. If V_in increases, I_s increases, extra current flows through Zener, but V_out stays at V_Z. JEE problems: (1) Find I_Z for given V_in and R_L. (2) Find R_L range for regulation. (3) Find R_s for desired regulation range. Key check: always verify I_Z > 0.