NUC[SERIES][LINE][PIN][FLASH][PKG][TEMP][VER]
│     │      │    │     │      │    │     │
│     │      │    │     │      │    │     └── Version (0, 1, etc.)
│     │      │    │     │      │    └── Temperature (N=normal, A=automotive)
│     │      │    │     │      └── Package type (A=QFN, etc.)
│     │      │    │     └── Flash size code
│     │      │    └── Pin code (LD=48, SD=64, VD=100, ZD=144)
│     │      └── Line number (23, 40, etc.)
│     └── Series (1=Cortex-M0, 2=Cortex-M0)
└── NuMicro prefix

M[LINE][PIN][FLASH][PKG]
│  │    │     │      │
│  │    │     │      └── Package code (AE=LQFP-48)
│  │    │     └── Flash size code
│  │    └── Pin code (LD=48, SD=64, LG=100, KI=128)
│  └── Line number (031=entry, 451=motor, 480=high-perf)
└── M-series prefix

NUC123LD4AN0
│  │  │ │││││
│  │  │ ││││└── Version 0
│  │  │ │││└── Temperature N (normal)
│  │  │ ││└── Package A (QFN)
│  │  │ │└── Flash 4 (64KB)
│  │  │ └── Pin LD (LQFP-48)
│  │  └── Line 23
│  └── Series 1 (Cortex-M0)
└── NUC prefix

M451LG6AE
│  │ │ ││
│  │ │ │└── Package E (LQFP variant)
│  │ │ └── Package A (LQFP)
│  │ └── Flash 6 (512KB)
│  └── Pin LG (LQFP-100)
└── M451 series (Cortex-M4 motor control)

// NUC series: Pin code is after line number
// NUC123LD4AN0 -> LD determines package

// M-series: Pin code is after series number
// M451LG6AE -> LG determines package

// N76E series: Package code is 2-letter prefix of pin count
// N76E003AT20 -> AT = TSSOP, 20 = pins

// NUC1xx and NUC2xx return generic series
if (upperMpn.matches("^NUC1\\d{2}.*")) return "NUC1xx";
if (upperMpn.matches("^NUC2\\d{2}.*")) return "NUC2xx";

// M-series returns exact line number
if (upperMpn.startsWith("M031")) return "M031";
if (upperMpn.startsWith("M451")) return "M451";
if (upperMpn.startsWith("M480")) return "M480";

// NAU88L must be checked before NAU88
if (upperMpn.matches("^NAU88L\\d{2}.*")) return "NAU88L";

// MCUs: Same series AND same pin count are replacements
// Audio Codecs: Same series are replacements (package variants OK)