In modern electronic systems, 5V power supplies and 5V signal lines are ubiquitous, including USB interfaces, MCU I/O, power inputs, and various digital circuits. To prevent chip damage caused by surges, voltage spikes, and electrostatic discharge (ESD), TVS diodes have become a core component of protection circuits.
However, faced with a large number of models and packages, how do you select the most suitable TVS diode for your 5V system? This guide takes an engineering and procurement perspective to help you quickly make the right choice.
📌Why are 5V TVS diodes so important?
Common transient threats in 5V systems include:
- ESD caused by cable plugging and unplugging
- Voltage spikes during power adapter switching
- Conducted surges from lightning strikes
- Internal switching transients within equipment
Lack of protection can damage sensitive components such as MCUs, USB chips, and communication interfaces. Choosing a suitable TVS diode provides nanosecond-level response, rapidly absorbing surge energy and ensuring system stability and reliability.
📌Six factors should be considered when selecting a 5V TVS diode:
1️⃣Reverse Working Voltage (VRWM)
A TVS diode must remain off (non-conducting) during normal operation.For a 5V system, a VRWM of around 5V is generally chosen.
If the VRWM is too low, it may mis-conduct during normal operation; if the VRWM is too high, the protection threshold increases, raising the risk.
2️⃣Breakdown Voltage (VBR)
VBR represents the surge voltage absorbed by the TVS diode after it turns on. For 5V, a TVS diode with a VBR ≈ 6.4V – 7V is typically chosen to achieve effective protection without affecting the normal power supply.
3️⃣Peak Pulse Current (IPPM) and Peak Pulse Power (PPK)
IPPM and PPK are used to determine the surge resistance of a TVS diode:
- IPPM (Maximum Instantaneous Current): Responds to ESD and surges
- PPK (Maximum Pulse Power): Indicates the TVS's surge resistance
💡Different applications have different requirements:
- USB, signal lines → Low capacitance preferred
- Power input, industrial environments → Require higher IPP/PPK (e.g., 1500W, 3000W)
4️⃣Packaging
Package type affects mounting method and surge protection, choosing the appropriate package is important.
5️⃣How to choose between unidirectional or bidirectional TVS diodes?
- Unidirectional TVS → Commonly used DC power cable
- Bidirectional TVS → Generally used for AC or bipolar signal lines such as USB, CAN, RS-485, etc.
6️⃣Parasitic capacitance (essential consideration for high-speed interfaces)
For USB/high-speed GPIO/data lines,
- Choosing models with low capacitance (< 3pF or < 1pF) to avoid signal distortion.
- Additionally, response time must be in the nanosecond range.
📌Semiware‘s 5V TVS Diode
📌Engineer Quick Selection Checklist (Highly Useful)
✔ What is the system's maximum normal operating voltage?
✔ Is VRWM ≥ System Voltage?
✔ Is VBR within the safety protection range?
✔ Does the surge rating need to be 600W / 1000W?
✔ Are there high-speed signals? Is low capacitance required?
✔ Does the package meet the heat dissipation and size requirements?
✔ Unidirectional or bidirectional?
✔ Does cost need to be optimized?
In summary, selecting a 5V TVS diode requires comprehensive consideration of factors such as VRWM, VBR, IPPM, package, parasitic capacitance, and polarity. Choosing the right device can effectively protect the system from surge and ESD damage, improving product stability and lifespan.
Welcome to explore Semiware's 5V TVS Diode product line. We support model replacement, sample requests, and engineer technical assistance!
📩bella.liu@semiware.com
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