This part is a kind of semiconductor called TC122-20.

Function of this product has thyristors (triacs).

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

ÒÐÈÀÊÈ ÒÑ122-20, ÒÑ122-25 Êîíñòðóêöèÿ òðèàêîâ m1, m2 - êîíòðîëüíûå òî÷êè èçìåðåíèÿ èìïóëüñíîãî íàïðÿæåíèÿ â îòêðûòîì ñîñòîÿíèè; m1 - â îäíîé èç äâóõ òî÷åê; Lmin = 1,7 ìì - äëèíà ïóòè äëÿ òîêà óòå÷êè ìåæäó îñíîâíûì âûâîäîì 2 è âûâîäîì óïðàâëÿþùåãî ýëåêòðîäà Ìàññà òèðèñòîðà íå áîëåå 11 ã. Òåïëîâûå ïàðàìåòðû Ïàðàìå òð Tjm Tjmin Ts tgm Tstg min R thjc Íàèìå íîâ àíèå , å äèíèöà èçìå ðå íèÿ Òèï òðèàêà ÒC122-20 ÒC122-25 Ìàêñèìàëüíî äîïóñòèìàÿ òåìïåðàòóðà ïåðåõîäà, oC 125 Ìèíèì [ ... ]

TC122-20 PDF Datasheet Download