Author ：Iflowpower – Portable Power Station Supplier
As long as it is a battery powered system, there is always this problem: you are wrong to install the battery, reverse polarity events, reverse polar events. System temporarily malfunction or permanent damage. The custom battery designed to fit the assembly helps to minimize the incorrect insertion and reverse polar opportunities, but is a Type AAA, AA type, C-type, and D-type cells.
Battery, or even CR123, CR2 and button lithium ion battery are also prone to failure. In the past, designers used mechanical structures to prevent electrical contact with battery terminals (if not inserted correctly). But the mechanical solution is far less.
They usually have special processing because the spring contacts are to control good mechanical components to ensure that it is good to be in contact with the battery correctly, but not inserted correctly. These narrow tolerances can result in long-term stability problems because the springs and contacts that must be used may be bent or faulty. Even normal use is normal, the normal insertion of the initial resend, can also cause contact fatigue, and limit the reliability over time.
But although these restrictions, mechanical solutions have always existed because they are the only practical ways that designers can use to prevent incorrect battery installations. Designed to prevent electrical solutions from reverse polar events caused by inverted batteries from being disputed. Because of the pressure drop during normal operation, it is usually not selected using a series diode.
It is not a good idea using diode grounding settings because the reverse polarity event may cause battery hazard discharge for a long time and make diode overheat. Differential MOSFETs to be complex, and may not be optimized or specific to prevent reverse polarity. The key specifications of the evaluation performance in the reverse polarity event may be lost, and this may make the designer have to estimate the performance characteristics of the data table and guess the safety working time period, is worrying.
Moreover, depending on the MOSFET application, they may have a controller or other cost high function. Multifunction ICs are sometimes equipped with circuits that prevent reverse polarity, which typically significantly adds the complexity of the circuit because they work in a positive bias environment and then work or not damaged in the reverse polarity mode. Therefore, multi-function IC has brought huge performance and / or cost price.
Due to the cost-effective trade-off, the typical implementation has a relatively limited reverse bias function (-2V or -6V). A dedicated anti-polarity protection device is an effective way to prevent erroneous insertion batteries However, recently, the emergence of dedicated reverse polar protection devices supply more viable electrical options for designers. Special devices (such as devices supplied by flying sight) represent one of the methods of preventing reverse polarity and cost performance and performance, is the best choice for battery power supply systems.
From reasons to measures: How to prevent battery instead? Figure 1. Displayed is a circuit that prevents reverse polarity from using a dedicated device from providing continuous and reliable protection. Designed to minimally reduce the voltage loss, and respond quickly and effectively under reverse bias conditions.
Overall cost is also good. SiteThetti diodes are usually cheaper than dedicated reverse polar protection devices, but once the operating current begins to increase, the total cost of Schottky method will begin to rise. For cost-effective trade-off, dedicated reverse polar protection devices are likely to be the most attractive electronic approach.
People will continue to make more mistakes on the battery, but designers prevent small unexpected ways will also change. After considering comprehensive, the dedicated reverse polarity protection device may completely replace complex mechanical solution over time. Something.
The reverse polarity is a steady-state reverse bias or negative transient result. This is a dangerous electrical situation, and once the system is factory factory, it is difficult to prevent. Reverse polarity is the actual threat in a variety of common applications, including mobile electronics, battery power systems, devices connected to automotive power supply, DC power toys, products with bucket jack connector, or any subjected to negative voltage heat Plug or inductance transient DC device.
Systems that support USB connection and / or USB charging are particularly affected. The following is some of the most common causes of reverse polarity:. In some cases, the charger has a reverse electrical contact or polarity can be set by the user, which leaving space for the error.
● The hot-swappable function bus using the USB can be easily connected or discontinuous mobile devices when the hot-swap function bus is charged. These inductance transients can swing bus to reverse polarity conditions. Although these swings are often very short, it is large.
More than 20V voltage rail swings have been measured in hot plug operations. This transient may affect the other devices on the disconnected device and the voltage rail. This problem will only be more serious when the charging current increases.
● The system that is powered by battery batteries that is not properly inserted can be faulty because the battery is not inserted correctly, and its positive negative is inserted. This is especially true for AAA type, AA type, C-type, and D-type cells, or CR123, CR2 or butter lithium-ion batteries. If the battery is inserted correctly, the mechanical solution prevents electrical contact with the battery terminal, but these solutions must be molded from the mold and can withstand the contact fatigue after a period of time.
● Developing the use of wall plugs in our country, there are fewer power infrastructure in the world, and there is less protection requirements. Therefore, power supply can transmit large voltage transients on the line. Indoor wiring makes the situation worse.
In the past, traditional incandescent lamps can help absorb and suppress transient energy on the power line, but there is no other inhibitory feature such as new types such as LED and CFL. Problems that have never been encountered by moving to LED and CFL. ● Insert the device into the car (or plane, train, etc.
) In many cases, the power supply adapter in the transportation power supply includes reverse polarity, but there are exceptions, especially in low cost replacement products. Uninformed users only put the device inserted into the lighter jack in the car, because he didn't realize that the lighter jack can cause the device failure. Since there are too many ways to trigger a reverse polar event, the designer must prevent the reverse polarity before the system will prevent damage to damage.
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