When selecting crystal diodes, attention should be paid to mastering the main parameters of the diode

(1) Maximum operating frequency fm (MC)

Due to the influence of the "inter electrode capacitance" of the PN junction, the highest frequency that the diode can be applied to cannot function properly if the frequency of the alternating current passing through the PN junction is higher than this value.

(2) Reverse breakdown voltage

When the reverse voltage applied to the PN junction increases to a certain value, the reverse current suddenly increases, indicating that the PN junction has been broken down and damaged (i.e. the reverse resistance value is equal to zero). This reverse voltage is called 'reverse breakdown voltage'. When the voltage applied across the diode reaches this value, the diode is immediately damaged.

(3) The maximum reverse operating voltage URM (V) represents the maximum allowable reverse voltage for the diode to operate normally for a long time. If this value is exceeded, there is a risk of P-N junction breakdown under the influence of environmental factors. In a rectifier circuit, because the positive and negative polarity of the AC voltage changes repeatedly, for AC power, the highest reverse operating voltage is the highest operating voltage of the diode, which is lower than the breakdown voltage.

(4) The maximum rectified current IoM (mA) represents the maximum forward current that a diode can operate normally for a long time. Because when current passes through a diode, it generates heat. If the forward current exceeds this value, there is a risk of burning out the diode. Therefore, when rectifying with a diode, the forward current (i.e. output current) flowing through the diode should not exceed the maximum rectified current.