Frequently Asked Questions |ROHM Semiconductor

What are absolute maximum ratings?
- Absolute maximum ratings are parameter limits that should never, under any circumstances, be exceeded. Doing so may result in component failure or, at the very least, deterioration, which will shorten life, leading to breakdown.

How much power can be supplied to a Zener diode?
- We must refer to the Pd-Ta derating curve for the particular model. Looking at the derating curve for the UDZS series below, at 25ºC the power dissipation is approximately 200mW, while at 87.5ºC this decreases to 100mW. The type of board must be taken into consideration as well.

What is thermal resistance Rth?
- This refers to the thermal resistance based on heat generated at the PN (or Schottky) junction. Specifically, Rth(j-a) is the thermal resistance from the junction to ambient and Rth(j-c) signifies the resistance from the junction to the terminal. The graph below is useful to determining Tj (junction temperature) during operation. Please note that Rth may vary depending on the size of the land pattern and board materials.

Are Material Safety Data Sheets (MSDS/SDS) available for transistors and diodes?
- In short, no. Transistors and diodes are considered 'articles', or manufactured items formed to a specific shape or design during manufacture which do not release or result in exposure to hazardous chemicals under normal conditions. As such they are exempted from requiring MSDS.