Teccor brand bidirectional alternistors are available with current ratings from 6A to 40A and voltages from 200V to 1000V as part of Littelfuse's broad line of thyristors. Littelfuse's alternistor is specifically designed for applications that switch highly inductive loads.

A special chip offers the same performance as two thyristors (SCRs) wired inverse parallel (back-to-back), providing better turn-off behavior than a standard triac. An alternistor may be triggered from a blocking to conduction state for either polarity of applied AC voltage with operating modes in Quadrants I, II,and III.

This new chip construction provides two electrically separate SCR structures, providing enhanced dv/dt characteristics while retaining the advantages of a single-chip device.

All alternistors have glass-passivated junctions to ensure longterm reliability and parameter stability. The glass-passivated junctions offer a reliable barrier against junction contamination.

The TO-218X package is designed for heavy, steady powerhandling capability. It features large eyelet terminals for ease of soldering heavy gauge hook-up wire. All the isolated packages have a standard isolation voltage rating of 2500 V rms.

Variations of devices covered in this data sheet are available for custom design applications. Consult the factory for further information. Notes:

• All measurements are made at 60 Hz with a resistive load at an ambient temperature of +25°C unless specified otherwise.
• Operating temperature range (Tj) is -40°C to +125°C.
• Storage temperature range (Ts) is -40°C to +125°C.
• Lead solder temperature is a maximum of 230°C for 10 seconds maximum >=1/16" (1.59 mm) from case.
• The case temperature (Tc) is measured as shown in the dimensional outline drawings. See Package Dimensions.