Improve the safety and reliability of power adapter design

In our daily life, we sometimes encounter some minor problems with the power adapter. Commonly used mobile phone chargers, PC power supplies, and power adapters of some small home appliances are damaged. So how can we design safe, reliable and durable products?

1, voltage stress

Power supply voltage stress is an important index to ensure the reliability of power supply. There are many devices in the power supply that have a specified maximum withstand voltage, such as the reverse withstand voltage of the diode, the maximum voltage of the IC, and the maximum withstand voltage of the input and output capacitors. Therefore, we must consider the maximum voltage that the device must withstand when designing. Then select the appropriate device according to the voltage, and finally perform actual testing to verify.

2, current stress

Power current stress is often closely related to thermal stress. For example, the diode current is 5A, but it is a limit parameter under the premise of satisfying thermal stress derating. Therefore, when we select a device, we must meet the current stress and thermal stress of the device at the same time; on the premise of meeting the thermal stress of the device, selecting a device with a suitable rated current value can ensure the reliability of the power supply.

3. Protection circuit

The protection circuit includes input undervoltage protection, input overvoltage protection, output overcurrent protection, output short circuit protection, and output overvoltage protection. In order to avoid abnormal operation of the power supply when the input voltage is too low, the power supply needs to add input undervoltage protection; to avoid the input voltage is too high, and the voltage stress during the period exceeds the standard, the power supply needs to add input overvoltage protection; to avoid output overcurrent and Short-circuit causes the device to overheat, magnetic saturation, etc. The power supply needs to add over-current protection and short-circuit protection; in order to avoid excessive output voltage of the power supply causing damage to the power load end, the power supply needs to add output over-voltage protection.

There are also EMC, safety regulations and overheating protection, which are all key factors affecting the reliability of the power supply.