28. TVS Diode for USB Data Line ESD Protection
1. Component Purpose
Every time a user plugs a USB cable, static discharge from their body can reach thousands of volts in nanoseconds. This ESD strike travels directly into the MCU’s USB data pins, which are rated for only ~4V absolute maximum.
A bidirectional TVS diode on each data line clamps ESD strikes to a safe voltage (~17V peak for nanosecond pulses — MCU pins can survive these brief transients). Critical: the TVS must have very low capacitance (≤5pF) to avoid distorting fast USB data signals.
Required: Bidirectional · Vstandoff 5–6.5V · Vclamp ≤17V · ≥40W · ≤5pF · SOD-882 · Littelfuse
2. How to Find It on DigiKey
Go to DigiKey.com → Circuit Protection → TVS - TVS Diodes
Apply these filters:
- Bidirectional Channels → 1
- Voltage - Reverse Standoff (Typ) → 5V to 6.5V range
- Voltage - Clamping (Max) → 17V or lower
- Capacitance → 5pF or lower
- Package / Case → SOD-882
- Manufacturer → Littelfuse Inc.
- Part Status → Active
Important: Capacitance is critical for USB. A TVS with 50pF capacitance would corrupt USB Full-Speed and Hi-Speed data. Always verify ≤5pF for data line TVS protection.
3. Key Specifications & What They Mean
| Specification | Required | Why |
|---|---|---|
| Direction | Bidirectional | ESD can strike in both polarities. |
| Standoff Voltage | 5–6.5V | Above USB 5V VBUS; no interference. |
| Clamping Voltage | ≤17V | Brief ESD pulse within MCU survival range. |
| Peak Pulse Power | ≥40W | Handles ESD energy. |
| Capacitance | ≤5pF | Preserves USB signal integrity. |
| Package | SOD-882 | Compact; fits near USB connector. |
| Manufacturer | Littelfuse | Company AVL requirement. |
| RoHS | Yes | Compliance required. |
4. Selecting a Safe, Production-Ready Part
The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?
Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide