Programmable Unijunction Transistors (PUT) Information
Programmable uni-junction transistors (PUT) are three-terminal thyristors that are triggered into conduction when the voltage at the anode exceeds the voltage at the gate. The PUT is similar to the UJT, but its intrinsic standoff ratio can be set by two external resistors. Hence, the name "programmable" is used. A PUT is a more advanced version of a unijunction transistor (UJT). In a programmable unijunction transistor, operating characteristics such as base-to-base resistance, intrinsic standoff voltage, valley current, and peak current can be programmed by setting the values of two external resistors. Applications for programmable unijunction transistors (PUT) include thyristor triggers, oscillators, pulse, and timing circuits, with frequencies up to 10 kHz. An integrated circuit can include not only an integrated circuit chip, but also a circuit transistor such as a programmable unijunction transistor.
Performance specifications for programmable unijunction transistors (PUT) include peak current (with RG of 10K ohms and 1M ohms), valley current (with RG of 10K ohms and 1M ohms), gate-to-cathode forward voltage, gate-to-cathode reverse voltage, gate-to-anode reverse voltage, anode-to-cathode voltage, peak non-repetitive forward current, peak repetitive forward current, peak repetitive forward current, DC forward anode current, DC gate current, power dissipation, storage temperature, operating junction temperature. Programmable unijunction transistors (PUT) can be packaged individually or in standard packaging for high-volume requirements, such as automatic insertion equipment.
Programmable unijunction transistors (PUT) that meet U.S. military specifications (MIL-SPEC) are manufactured according to standards described in MIL-STD-750 (Test Method Standard for Semiconductor Devices) and MIL-HDBK-6100 (Military Handbook, List of Case Outlines and Dimensions for Discrete Semiconductor Devices). Like other components made of semiconductor material, programmable unijunction transistors (PUT) that are marketed in European Union (EU) nations should be manufactured in compliance with the Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) Directives. RoHS requires all manufacturers of electronic and electrical equipment sold in Europe to demonstrate that their products contain only minimal levels of the following hazardous substances: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyl and polybrominated diphenyl ether. RoHS will become effective on July 1, 2006. By definition, lead-free devices contain less than 1000 ppm lead by weight.