BOS1921 BOM Selection

Question:

How do I choose the external components around the BOS1921?

Answer:

The best way to approach component selection for the BOS1921 is to rely on the existing documentation and tools, and use them together rather than in isolation. Here is the recommended approach:

1. Start with the BOM Selection Application Note (written for the BOS1901)
   Even though this application note was developed for the BOS1901, the selection methodology applies across the entire product line, including the BOS1921.
   It walks through the whole process, also referencing to the other available tools.

   This should be your main reference for understanding why certain components are chosen and their key features.

2. Use the Online BOM Calculator
   Once each component use is understood, use the BOM Calculator to quickly determine component requirements for your specific operating conditions. Note these requirements are a starting point that still can be refined after testing.

3. Cross-check with the BOS1921 Datasheet
   The datasheet remains the authoritative source for:

   • Electrical limits and ratings

   • Recommended operating conditions

   • Reference schematics

   Make sure all selected components keep the system comfortably within the specified limits.

4. Review the Development Kit User Guide
   The DK User Guide provides a concrete, validated example of a working implementation. Reviewing the evaluation board schematic and BOM is a good way to:

   • Get familiar with the IC operation.

   • Gain confidence before prototyping.

   • Confirm practical component selections by swapping the devkit components by your selection.

   • Benchmark your design choices.

5. Don’t Forget the Inductor Derating Application Note
   Inductor behavior under high-voltage switching is often underestimated. The derating application note explains how inductance reliability under voltage should approached.