Thyristor Semiconductor Products Page 72 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1007 Triac or Alternistor MT2 0.1f 100 Load MT1 Hot Neutral 120/240 V ac G 22 Input R in 1 6 5 4 3 2 Load could be here instead of lower location Zero Crossing Circuit Figure AN1007.14 Zero Crossing Turn-on Opto Triac Driver R in 1 G 120/240 V ac 2 3 0.1F Load 6 4 5 22 K A 100 G A K Non-sensitive Gate SCRs Load could be here instead of lower location Zero Crossing Circuit Input Figure AN1007.15 Zero Crossing Turn-on Non-sensitive SCR Driver R in 1 G 120/240 V ac 2 3 0.1 F Load 6 4 5 22 K A 100 G A K Sensitive Gate SCRs Load could be here instead of lower location Zero Crossing Circuit Input 1 K * Gate Diodes to Have Same PIV as SCRs Figure AN1007.16 Zero Crossing Turn-on Opto-sensitive Gate SCR Driver Time Delay Relay Circuit By combining a 555 timer IC with a sensitive gate Triac, various time delays of several seconds can be achieved for delayed activation of solid state relays or switches. Figure AN1007.17 shows a solid state timer delay relay using a sensitive gate Triac and a 555 timer IC. The 555 timer precisely controls time delay of operation using an external resistor and capacitor, as illustrated by the resistor and capacitor combination curves. (Figure AN1007.18) 555 10 K 0.1 F 0.01 F 1 F 1 K LOAD MT2 MT1 G 10 M 1N4740 3.5 K 3 W 10 F + _ 1N4003 -10 V 250 V 120 V 60 Hz 4 3 8 2 5 1 6 7 R C Figure AN1007.17 555 timer circuit with 10 second delay 10ms 100ms 1ms 10ms 100ms 1.0 10 100 0.001 0.01 0.1 1.0 10 100 td TIME DELAY (s) C, (CAPACITANCE) (F) 10 M 1 M 100 K 10 K 1 K Figure AN1007.18 Resistor (R) and capacitor (C) combination curves IR Motion Control An example of a more complex Triac switch is an infrared (IR) motion detector controller circuit. Some applications for this circuit are alarm systems, automatic lighting, and auto doorbells. Figure AN1007.19 shows an easy- to-implement automatic lighting system using an infrared motion detector control circuit. A commercially available LSI circuit HT761XB, from Holtek , integrates most of the analog functions. This LSI chip, U2, contains the op amps, comparators, zero crossing detection, oscillators, and a Triac output trigger. An external RC that is connected to the OSCD pin determines the output trigger pulse width. ( Holtek Semiconductor Inc . is located at No.3, Creation Road II, Science-Based Industrial Park, Hsinchu, Taiwan, R.O.C.) Device U1 provides the infrared sensing. Device R13 is a photo sensor that serves to prevent inadvertent triggering under daylight or other high light conditions. Choosing the right Triac depends on the load characteristics. For example, an incandescent lamp operating at 110 V requires a 200 V, 8 A Triac. This gives sufficient margin to allow for the high current state during lamp burn out. U2 provides a minimum output Triac negative gate trigger current of 40 mA, thus operating in QII & QIII. This meets the requirements of a 25 mA gate Triac. Teccor also offers alternistor Triacs for inductive load conditions. This circuit has three operating modes (ON, AUTO, OFF), which can be set through the mode pin. While the LSI chip is working in the auto mode, the user can override it and switch to the test mode, or manual on mode, or return to the auto mode by switching the power switch. More information on this circuit, such as mask options for the infrared trigger pulse and flash options, are available in the Holtek specifications. Thyristors Used as AC Static Switches and Relays (continued)

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