other devices.pdf - 6.0 INTRODUCTION TO OTHER ELECTRONIC DEVICES 1 2 3 4 Silicon Controlled Rectifier(SCR TRIAC DIAC UJT(Uni-junction transistor 6.1

other devices.pdf - 6.0 INTRODUCTION TO OTHER ELECTRONIC...

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6.0 INTRODUCTION TO OTHER ELECTRONIC DEVICES 1. Silicon Controlled Rectifier (SCR) 2. TRIAC 3. DIAC 4. UJT (Uni-junction transistor)
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6.1 SILICON CONTROLLED RECTIFIER (SCR) 6.1.1 INTRODUCTION - SCR is a 4 layer component - Three terminals : anode, cathode, and gate - SCR mostly used as a switching component in the control application power.
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6.1.2 PHYSICAL STRUCTURE6.1.3 SCHEMATIC SYMBOL
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6.1.4 I-V CHARACTERISTICS VBRF1VBRF2IG2>IG1IG1=0 VFVRIFIRBreakover voltage Forward Blocking Current Holding current Reverse Blocking Current SCR “OFF”SCR”ON”Forward Breakover voltage
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- SCR characteristic curve is close with normal diode characteristic curve except there is some part in the early stage that show forward current been blocked for a while - In forward bias (VF), when IG=0, there is no anode current (IA) that can be transmit by SCR except a few current leakage. - Although VFincreased, there is no IAexcept leaking current increased. The current in this level is called Forward Blocking Current. - In one situation, when IGstill 0 and VFbeen increased, it will reach at one value of voltage where’s IAsuddenly transmit and increase quickly. At the time, VF value peculiar named Forward Break over Voltage, VBRF1. - If there is IG(cause by positive voltage to the gate), that is inside the figure been labeled IG2, forward breakover voltage situation will happen earlier (VBRF2). VBRFcan be decreased by increasing the value of IG. After that, if IGis barrel to a higher value, SCR will act as a normal diode.
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- In reverse biased (VR), SCR will not transmit current except a little bit of leaking current or reverse blocking current. If VRis too high until it reach the reverse breakover voltage, SCR will act like a normal diode in reverse bias condition.
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  • Summer '15
  • paul june
  • SCR, (SCR)

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