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Power adapter output overvoltage and undervoltage protection
time2006/05/29
- A good power adapter must have well-established circuit protection, so that it can better ensure the safety and stability of the power supply. Today, we will introduce the overvoltage protection and undervoltage protection of the power adapter.
A good power adapter must have well-established circuit protection, so that it can better ensure the safety and stability of the power supply. Today, we will introduce the overvoltage protection and undervoltage protection of the power adapter.
Output overvoltage protection
When voltage control is lost, excessive output voltage can be caused either in the linear power supply or in the power adapter. In linear power adapters and some switching converters, there is a connected DC path between the input and output circuits, so shorting the power control device will result in a large uncontrollable output. This type of circuit requires a powerful overvoltage clamping technique. Usually, a thyristor overvoltage protection circuit is used to short-circuit the output from the surface to burn the fuse.
In off-line power adapters, the output and input are isolated by a highly insulated transformer. In such systems, most faults will only result in low voltage or zero voltage output. The need for sharp protection against overvoltage is not so strong and is often considered to be inconsistent with volume limitations. In such systems, The independent signal voltage clamping system functioning by the converter drive circuit can achieve satisfactory overvoltage protection.
The design goal is that failure of individual components in the power adapter will not cause an overvoltage condition. Because the usual signal level clamping techniques rarely meet this goal (for example, insulation faults cannot be fully protected), in the most stringent power adapter designs, it is still necessary to consider overvoltage protection circuits and fuses. Technology. The overvoltage protection circuit also provides some protection against external overvoltage conditions.
Output undervoltage protection
The output undervoltage is caused by excessive transient current demand and power supply stop. In power adapters, there is often a significant amount of energy stored in the input capacitor that maintains the output voltage during a short-term power supply stop. However, after limiting the rated current and output voltage drop, the transient current demand can still cause an undervoltage.