(在顺偏压区)Inthereversebiasregion.PPT

* * * * * * * * * * * * * * * * * * * * * * Ex. 1.2 * Determine the dc resistance level for the diode at ID = 2 mA ID = 20 mA VD = －10 V The resistance depends on the amount of current (ID) in the diode. The voltage across the diode is fairly constant (26mV for 25?C). rB ranges from a typical 0.1? for high power devices to 2? for low power, general purpose diodes. In some cases rB can be ignored. AC, or Dynamic, Resistance In the forward bias region:(在順偏壓區) In the reverse bias region: The resistance is essentially infinite. The diode acts like an open. * 電阻要視二極體上之電流 (ID) 量而定。 二極體的電壓降相當地固定 (26mV for 25?C)。 rB 範圍在高功率裝置之典型值自 0.1? 到低功率與一般功能二極體 的2?， 在某些狀況下的 rB 可以忽略。 在逆偏壓區: 電阻在本質上是無限的，二極體動作像是開路。 AC resistance can be determined by selecting two points on the characteristic curve developed for a particular circuit. Average AC Resistance * 交流電阻可以在一特定電路的特性曲線上選取兩點來計算決定。 VF (順向偏壓) ， forward voltage at a specific current and temperature IF (最大順向電流) ， maximum forward current at a specific temperature IR (最大逆向電流)， maximum reverse current at a specific temperature PIV or PRV or V(BR) (最大逆向電壓)， maximum reverse voltage at a specific temperature Power dissipation (功率消耗) ， maximum power dissipated at a specific temperature C(電容大小), capacitance levels in reverse bias trr (逆向恢復時間) ， reverse recovery time Temperatures (溫度) ， operating and storage temperature ranges Diode Specification Sheets (二極體特性表) Data about a diode is presented uniformly for many different diodes. This makes cross-matching of diodes for replacement or design easier. * 二極體數據資料是代表許多不同二極體的一致性。這使得二極體在取代或設計上的交叉配對更容易些。 In reverse bias, the depletion layer is very large. The diode’s strong positive and negative polarities create capacitance, CT. The amount of capacitance depends on the reverse voltage applied. In forward bias storage capacitance or diffusion capacitance (CD) exists as the diode voltage increases. Diode Capacitance * 在逆偏壓下的空乏層是非常大,二極體的強大正極性與負極性所產生的電容CT, 這電容量要視外加的逆向電壓而定。 在順偏壓下存在的儲存電容或擴散電容 (CD) 是隨著二極體電壓增