computer. engeeneering

First step is to choose a thyristor with forward breakover voltage (say 800V) higher than thenormal working voltage. The benefit is that the thyristor will be in blocking state with normal working voltage applied across the anode and cathode with gate open. When we require theturning ON of a SCR a positive gate voltage between gate and cathode is applied. The pointto be noted that cathode n- layer is heavily doped as compared to gate p-layer. So when gate supply is given between gate and cathode gate p-layer is flooded with electron from cathoden-layer. Now the thyristor is forward biased, so some of these electron reach junction J2 .As aresult width of 2 breaks down or conduction at J2 occur at a voltage less than VBO . As increases VBO reduces which decreases then turn ON time. Another important point isduration for which the gate current is applied should be more then turn ON time. This meansthat if the gate current is reduced to zero before the anode current reaches a minimum valueknown as holding current, SCR can't turn ONIn this process power loss is less and also low applied voltage is required for triggering. Thysistor Thyristor is a four layer three junction pnpn semiconductor switching device. It has 3 terminals these are anode, cathode and gate. SCRs are solid state device, so they are compact,possess high reliability and have low loss. Anode A P N Gate P N G Cathode SCR is made up of silicon, it act as a rectifier; it has very low resistance in the forward direction and high resistance in the reverse direction. It is a unidirectional device. 1. Static V-I characteristics of a Thyristor The circuit diagram for obtaining static V-I characteristics is as shown Develop an ALP to transfer the content of ROM location starting from 300H to RAM location 50H. After execution of the program, memory content should be as follows ROM location RAM location 300H: 10H 50H: 20H 301H: 20H 51H: 40H 302H: 30H 52H: 60H 303H: 40H 304H: 50H 305H: 60H