charged device model (cdm)

**Charged Device Model (CDM)** is the **ESD test model that simulates the most common real-world ESD event in manufacturing** — where the IC package itself accumulates charge (from sliding, handling, pick-and-place) and then rapidly discharges when a pin contacts a grounded surface. **What Is CDM?** - **Mechanism**: The entire package is charged. When *any* pin touches ground, the stored charge exits through that pin in < 1 ns. - **Waveform**: Extremely fast. Rise time ~100-250 ps. Duration ~1-2 ns. Peak current 5-15 A (much higher than HBM). - **Classification**: C1 (125V), C2 (250V), C3 (500V), C4 (750V), C5 (1000V). - **Standard**: ANSI/ESDA/JEDEC JS-002. **Why It Matters** - **Most Common Failure Mode**: CDM events are the #1 cause of ESD damage in automated assembly lines. - **Internal Damage**: The fast discharge can destroy thin gate oxides internally without visible external damage. - **Design Challenge**: Protecting against CDM requires careful power clamp and core clamp design. **CDM** is **the self-inflicted lightning strike** — modeling the moment a charged chip grounds itself and sends a destructive current surge through its most sensitive internal structures.