similarity-mosfet

# MOSFET Similarity Calculator Skill Guidance for working with `MosfetSimilarityCalculator` in the lib-electronic-components library. --- **For metadata-driven similarity architecture**, see `/similarity-metadata`: - SpecImportance levels (CRITICAL, HIGH, MEDIUM, LOW, OPTIONAL) - ToleranceRule types (exactMatch, percentageTolerance, minimumRequired, etc.) - SimilarityProfile contexts (DESIGN_PHASE, REPLACEMENT, COST_OPTIMIZATION, etc.) - Calculator integration patterns and gotchas --- ## Overview The `MosfetSimilarityCalculator` compares MOSFETs based on: - **Equivalent groups** - Cross-manufacturer equivalents - **Channel type** - N-channel vs P-channel - **Electrical characteristics** - Voltage, current ratings ## Applicable Types ```java ComponentType.MOSFET ComponentType.MOSFET_INFINEON ComponentType.MOSFET_ST ComponentType.MOSFET_NXP // Any type starting with "MOSFET_" ``` Note: Returns `true` for `null` type to handle unrecognized MOSFETs. ## Similarity Thresholds ```java HIGH_SIMILARITY = 0.9; // Equivalent parts MEDIUM_SIMILARITY = 0.7; // Similar specs LOW_SIMILARITY = 0.3; // Different channel type or specs ``` ## Equivalent Groups The calculator knows these cross-manufacturer equivalents: | IRF Part | Equivalents | |----------|-------------| | IRF530 | STF530, IRF530N, STF530N | | IRF540 | STF540, IRF540N, STF540N | | IRF9530 | STF9530, IRF9530N (P-channel) | | IRF9540 | STF9540, IRF9540N (P-channel) | ## Channel Type Rules **N-channel and P-channel MOSFETs always return LOW_SIMILARITY (0.3)** | Part | Channel | Note | |------|---------|------| | IRF530 | N-channel | Standard power MOSFET | | IRF9530 | P-channel | The "9" indicates P-channel | | IRF540 | N-channel | Higher current than IRF530 | | IRF9540 | P-channel | Higher current P-channel | ```java calculator.calculateSimilarity("IRF530", "IRF9530", registry); // Returns 0.3 (N vs P channel) ``` ## Manufacturer Prefix Handling The calculator normalizes manufacturer prefixes: | Manufacturer | Prefix | Example | |--------------|--------|---------| | International Rectifier | IRF | IRF530 | | STMicroelectronics | STF | STF530 | | Vishay | IRF, SIF | SIF530 | | Infineon | IPD, IPB | IPD530 | ```java calculator.calculateSimilarity("IRF530", "STF530", registry); // Returns 0.9 (same part, different manufacturer) ``` ## Suffix Handling Common suffixes that don't affect equivalence: - `N` - Updated version (IRF530N ≈ IRF530) - `PBF` - Lead-free - `L` - Logic level gate ```java calculator.calculateSimilarity("IRF530", "IRF530N", registry); // Returns 0.9 (same MOSFET, N is just version) ``` ## Test Examples ```java // Cross-manufacturer equivalent calculator.calculateSimilarity("IRF530", "STF530", registry); // Returns 0.9 // N-channel vs P-channel calculator.calculateSimilarity("IRF530", "IRF9530", registry); // Returns 0.3 // Different current ratings calculator.calculateSimilarity("IRF530", "IRF540", registry); // Returns < 0.9 (14A vs 28A) // Non-MOSFET parts calculator.calculateSimilarity("LM358", "LM324", registry); // Returns 0.0 ``` ## Implementation Notes - Returns 0.0 for non-MOSFET MPNs - The `9` in part number typically indicates P-channel - Symmetry: `sim(A,B) == sim(B,A)` --- ## Learnings & Quirks ### Part Number Patterns - IRF5xx/IRF6xx: N-channel power MOSFETs - IRF95xx/IRF96xx: P-channel equivalents - The xx number often indicates Vds rating (e.g., 530 ≈ 100V) ### Cross-Manufacturer Equivalence - STF = ST equivalent to IRF - Many manufacturers make "drop-in" replacements - Check Vds, Rds(on), and Id specs for true equivalence ### Package Variants - TO-220: Standard through-hole - TO-220F: Isolated tab - D-PAK: Surface mount - Same electrical part in different package = HIGH_SIMILARITY <!-- Add new learnings above this line -->