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The voltage sharing problem occurs when used in series, which causes the reverse voltage of a certain diode to be too high and damaged, disturbing the normal operation of other diodes. External circuit design can cause stray inductance and capacitance, which can cause uneven voltage problems in high-voltage high-frequency environments. When the voltage drop on D2 from the external voltage U increases reaches the critical point, the drop of D1 is relatively small and still in the safe and stable region due to its large reverse saturation currents.