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This post was last edited by *aojiaoya0546 on 2016-5-29 22:49. In the process of research, development, and design of new switching power supply adapters, engineers typically add various protective measures to these new products, in order to prevent short circuits or damage to components during use, which could otherwise reduce their operational lifespan. In today’s article, we will share with you four protective measures that can extend the lifespan of adapters. Let’s take a look together. Method 1: Overpower delay shutdown protection. As a highly effective output overload protection technique, overpower delay shutdown protection has now been widely adopted in power adapter products manufactured in China. In delayed trip systems, short-term transient currents are permitted; the power supply is only turned off when the current stress exceeds the safe value for an extended period of time. The provision of short transient currents will not compromise the reliability of the power supply, nor will it have a significant impact on its cost. Only the requirement for a continuous current over a long period affects the cost and size of the circuit. Method 2: Flyback over-power limit protection method. In addition to the two methods mentioned above, the flyback over-power limit protection method is also an important measure that can ensure the safe operation of switch-mode power supply adapters; it is currently widely used in the development of adapters and in the manufacturing processes of manufacturers in China. This protection technique is an extension of the upper-speed mode; in the adapter circuit that uses this protection method, there is a dedicated circuit for monitoring the primary current and secondary voltage, in order to reduce power when the output voltage drops. In this way, the output current is reduced when the load resistance decreases, preventing the components on the secondary side from being damaged by excessive stress; however, a drawback is that locking occurs when used with nonlinear loads. Method 3: Constant power limit protection. The constant input power limit protection method is the fourth type of protection technology for switch-mode power supply adapters that we will be introducing to you today. It is also a commonly used output protection technique both domestically and internationally, and it plays an essential role in the development of laptop adapters as well as mobile phone adapters. The protection principle of this method lies in protecting the primary circuit by limiting the maximum transmission power. However, in flyback converters, this technique can hardly protect the secondary output components. For example, in a discontinuous flyback converter, the peak current on the primary side is already limited, which thus determines the limited transfer power. Method 4: Pulse-by-pulse overpower or overcurrent limitation. In the development of new switch-mode power supply adapters, pulse-by-pulse overpower and overcurrent limitation is essential. This type of limitation for each individual pulse constitutes a very effective method for protecting against output overload in practical applications, and this technique is often used in conjunction with additional secondary-side current-limiting protections. In previous switching devices, the input current had to be monitored in real time. If this current exceeds the specified limit current value, the conduction pulse will be terminated. In a non-reinforced flyback converter, the maximum current determines the power of the circuit; such a type of protection circuit thus functions as an actual power-limiting protection circuit.