Vishay is providing detailed thermal characteristics for newly released optocouplers and solid-state relays (SSRs) that have total power dissipation of 200 mW and higher. The thermal data will allow designers to more accurately simulate heat distribution and thermal impedance for optocoupler and SSR devices. Vishay offers a compact thermal model as well as a Flotherm model for those customers who use this software from Flomerics. Common thermal characteristics of junction-to-ambient or junction-to-case thermal impedance are readily available, as well as all the other components in the thermal network. Designers can use these values to calculate temperatures for a given operating condition. The thermal behavior for a given application will be dependent on the type of PCB, the specifics of the layout, and the thickness of the copper traces.

The Flotherm analysis software tool used to model Vishay's optocoupler and solid-state relay devices uses computational fluid dynamics techniques to predict the in situ airflow and temperature environment of components and PCBs in industrial equipment, computers, telecommunication systems, and other end products. This enables the designer to identify the source of any over-heating, and to devise and test appropriate design modifications quickly and easily. The first Vishay optocoupler products for which the detailed thermal characteristics are available are the 60-V, 10- VO1400AEFT2 SSR, the 0.5-A VO3150 IGBT driver, the 1.5k-V/µs VO3063 and VO3062 and 5-kV/µs VO4154, VO4156, VO4157, and VO4158 zero-crossing phototriacs; and the 5-kV/µs VO4254, VO4256, VO4257, and VO4258 non-zero-crossing phototriacs.