When winter arrives, the human body can accumulate static electricity reaching tens of thousands of volts. As the year comes to an end and projects are in their final stages, it's crucial to avoid touching a live motherboard directly with your hands—this could cause serious damage!
**Figure 1: Human hands and circuit boards should not be too close?**
It’s common knowledge among electronics engineers that direct contact between human hands and a circuit board is risky. But why is this so?
### **First, the Dangers of Static Electricity**
In various environments, the voltage carried by the human body can range from hundreds to tens of thousands of volts. When you touch electronic components, this static charge can discharge, potentially damaging sensitive parts and reducing device reliability. In extreme cases, it may even lead to component failure or product scrap.
Additionally, electrostatic discharge (ESD) can emit radio waves at certain frequencies, interfering with nearby microprocessors and causing software malfunctions. This can severely impact the normal operation of the device.
**Figure 2: Be cautious of static electricity**
To prevent such issues, it's essential to follow proper procedures during production and daily work, such as wearing an anti-static wrist strap correctly. Avoid direct contact with electronic components, especially when they're powered on.
### **Second, the Impact of Static Electricity on the Core Board's Feedback Circuit**
Take the M3352 industrial-grade core board (based on the Cortex-A8 architecture) as an example. This core board has passed rigorous electromagnetic compatibility (EMC) testing, including static discharge, surge, pulse groups, and conducted disturbances.
In a powered-on state, if an engineer touches the area marked in yellow in Figure 3, it can trigger a system restart. Why does this happen?
**Figure 3: M3352 Industrial Grade Core Board**
The yellow-circled area (R80, C116, R79, R78) represents the feedback and compensation network for the 3.3V DC-DC power supply, as shown in Figure 4.
**Figure 4: System Power Circuit**
When a person touches this area, their body introduces interference through equivalent resistance. This changes the characteristics of the feedback loop, potentially causing oscillation and unstable DC-DC output voltage.
If the DC-DC output becomes unstable, the system might restart. In more severe cases, the main chip on the board could be damaged due to excessive voltage.
**Figure 5: Motherboard with No Touch**
### **Third, How to Prevent Static Electricity**
Here are some effective methods:
#### **1. Anti-Static Cordless Wrist Strap**
**Figure 6: Anti-Static Cordless Wrist Strap**
Using the principle of corona discharge, these straps release accumulated static electricity into the air when the charge exceeds a threshold. They’re convenient, mobile, and discharge static in under 0.5 seconds.
#### **2. Anti-Static Wrist Strap**
**Figure 7: Anti-Static Wrist Strap**
These straps make direct contact with the skin and ground the static charge quickly. They discharge in less than 0.1 seconds, making them highly effective.
#### **3. Anti-Static PU Coated Gloves**
**Figure 8: Anti-Static PU Coated Gloves**
These gloves prevent static electricity from transferring to the board via hand contact. The conductive wires on the back of the gloves are spaced 10 mm apart, offering good protection.
### **Fourth, Core Board Anti-Static Protection Measures**
Let’s look at ZLG Zhiyuan Electronics’ M3352 industrial-grade core board as an example. It’s designed to withstand high levels of ESD and other electromagnetic interferences.
**Figure 9: M3352 Industrial Grade Core Board**
**Figure 10: M3352 Evaluation Kit**
#### **Hardware Protection – Electromagnetic Compatibility Level 4**
- **Electrostatic Discharge Immunity**: Air discharge ±15kV, contact discharge ±8kV
- **Electrical Fast Transient Pulse Group**: 5kHz and 100kHz, 300ms per pulse group
- **Surge Immunity**: 2kV capacitive coupling with gas discharge tube, 1 time per minute
- **Conducted Disturbance Immunity**: 3V capacitive coupling with gas discharge tube, 150kHz–80MHz
#### **Software Protection – Dual System Architecture Design**
The M3352 uses a dual-system design to ensure stability. If the main storage system (Flash) encounters bad blocks or corruption due to static interference or power loss, the backup system automatically activates. This ensures continuous and stable operation of the product.
110KV-220kv Oil Immersed Transformer
110Kv-220Kv Oil Immersed Transformer,Anti - Interference 110Kv Transformer,Low Loss 110Kv Oil-Immersed Transformer,High Load Capacity 110Kv Oil-Immersed Transformer
Tianhong Electric Power Technology Co., Ltd , https://www.tianhongtransformer.com