To ensure the stability and safety of 5V and 12V power supplies, the following measures can be taken:

Short Circuit Protection (SCP)

Power supplies should have short-circuit protection that disables the power supply and locks it when a short circuit is detected at the output to prevent damage. Separate short-circuit and overcurrent protection should be provided for 5V and 12V power supplies.

No-Load Condition

The power supply should not be damaged or create hazardous conditions when all DC output connectors are disconnected from the load, potentially locking in an off state.

Overcurrent Protection (OCP)

Design current protection to limit the current within safe operating conditions. It’s recommended that the power supply locks in an off state during overcurrent events to protect the power supply and system safety.

Over Temperature Protection (OTP)

Power supplies should include over-temperature protection sensors that disable the power supply when triggered at a preset temperature point to prevent overheating due to internal current overload or fan failure.

Output Bypass

The output end may be connected to the power supply casing and connected to the system casing by system components.

Independent Current Limit for 12V2

The 12V rail on the 2×2 power connector should be an independent current-limited output to meet the requirements of UL and EN 60950.

Insulation Requirements

Power supplies should have basic insulation and supplementary insulation to prevent electric shock in case of basic insulation failure. Minimum insulation requirements for power supplies include: reinforced insulation between primary and secondary, with a minimum withstand voltage of 3000Vrms; basic insulation between primary and ground, with a minimum withstand voltage of 1500Vrms.

Protective Earth

Class I equipment must have a protective earth conductor, which must be green/yellow or transparent if insulated. The resistance between grounded parts and grounding terminals should not exceed 0.1Ω, with a maximum test voltage of 12V and a test current that can be AC or DC but should not exceed 25A.

Clearance and Creepage Distance

Adequate clearance and creepage distances should be designed based on working voltage and contamination conditions to ensure insulation safety.

Flammability

The design should avoid high temperatures or isolate flammable materials from high-temperature components. Use materials with low flammability, both internally and for the casing.

Earth Leakage Current

The earth leakage current for Class II equipment should not exceed 0.25mA, 0.75mA for hand-held Class I equipment, and 3.5mA for other Class I equipment.

By implementing the above measures, the stability and safety of 5V and 12V power supplies can be ensured, protecting electronic equipment and users from power failures and safety risks.