Thyristor Semiconductor Products Page 37 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1003 Summary 120VAC (HIGH) AC (RETURN) WHITE RV1 VARISTOR R1 47 C3 .1F +5V R2 1M 2000 W D1 1N4001 D1 1N4001 R3 20M D3 1N5231 C1 220F C2 .01F VDD GP5 GP4 GP3 VSS GP0 GP1 GP2 R6 470 R7 100 Q1 L4X8E5 Q2 Q4025L6 R4 470 R5 470 S2 S1 INCREASE HEAT DECREASE HEAT VDD U1 12C508 Figure AN1003.24 Microcontroller Heater Control The load currents chosen for the examples in this application note were strictly arbitrary, and the component values will be the same regardless of load current except for the power Triac or SCR. The voltage rating of the power Thyristor devices must be a minimum of 200 V for 120 V input voltage and 400 V for 240 V input voltage. The use of alternistors instead of Triacs may be much more acceptable in higher current applications and may eliminate the need for any dv/dt snubber network. For many electrical products in the consumer market, competitive Thyristor prices and simplified circuits make automatic control a possibility. These simple circuits give the designer a good feel for the nature of Thyristor circuits and their design. More sophistication, such as speed and temperature feedback, can be developed as the control techniques become more familiar. A remarkable phenomenon is the degree of control obtainable with very simple circuits using Thyristors. As a result, industrial and consumer products will greatly benefit both in usability and marketability. Phase Control Using Thyristors (continued)

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