Now more and more people have bought cars for transportation, long-distance travel, and delivery of goods, which can be said to be a part of life. People spend more and more time in the car and sometimes use their mobile phones to watch videos or turn on the computer for office work in the car. As people stay longer in the car, the car charger can charge mobile phones, laptops, and other office equipment in the car. Naturally, it is as important as a charging treasure, and it is an indispensable and important accessory for every car owner.
The car charger is inserted into the cigarette lighter jack, powered by the car battery, the car outputs 12V, the truck outputs 24V, and the car charger converts the voltage 5V/9V/10V/12V acceptable to the mobile phone, etc. Some high-power car chargers can also be powered by the built-in buck-boost boosts the voltage to 15V and 20V to charge mobile phones and laptops. Low-power car chargers usually use a step-down architecture, which can meet general mobile phone charging. For example, the following are two types of boosted high-power car chargers.
With the substantial increase in the charging power of mobile phones, through the built-in high-efficiency and high-power synchronous buck-boost circuit, the output power of the car charger has also followed in the footsteps of the charger. The output power has reached 100W, the upper limit of USB PD3. normal use of the computer.
The charging head network tested the new SW7203 bidirectional synchronous buck-boost controller launched by Zhirong. The test adopts 12V input, and the boost output is 20V5A to simulate the scene of 100W charging of a notebook. The input current of the analog battery display panel has reached 8.7A, which means that when we use a high-power car charger to charge notebooks and mobile phones in the car, the maximum current may be close to the upper limit of the output current of the cigarette lighter of 10A. The following is a test of 100W for the load high-power car filling object.
With the popularity of USB PD, many brands have launched car chargers that support 100W output. Through the dismantling of various car chargers through the charging head network, these car chargers all use high-current thimbles instead of traditional ones without exception. Positive spring.
So what are the benefits of using a high-current thimble instead of a spring? It can make many manufacturers abandon the use of spring-positive poles. The high-current thimble must have many advantages so that manufacturers will use it unanimously. The following are the actual use of thimbles with two different structures.
The 160W car charger has a built-in 100W output buck-boost circuit and two independent step-down circuits, a total of three independent outputs, providing an output power of 100W+30W+30W. It can be seen from the disassembly that the car charger uses a combination of multiple circuit boards to weld, and the two larger circuit boards are connected through the small plate of the positive thimble.
Because the high-power car charger has a built-in buck-boost circuit, there are many components and the design is more complicated. Usually, multiple PCBs are combined and welded inside. Soldering the thimble with a small board can, on the one hand, fix and support the structure of the internal circuit board. On the other hand, the heat generated by the positive thimble when a large current flows can also be dissipated through the PCB to avoid high temperatures from affecting the performance of the inner spring of the POGO PIN.
The high-current thimble used for the positive pole of the car charger consists of three parts, which are divided into a solid needle shaft, which provides an elastic spring, and a shell needle tube. Put the spring and the needle shaft into the needle tube, and then rivet the top of the needle tube to fix the needle shaft to produce a thimble. Among them, the thimble head is solid, and the shell is thick-walled, with high mechanical strength and flow capacity. The current flows directly from the needle shaft and needle tube throughout the whole process, and the direct contact does not pass through the spring, which avoids the problem of spring heating and aging.
And the high-current PINs are all thickly gold-plated, with good contact and wear resistance, thick walls and thick gold-plated, and low resistance. Moreover, the gold-plated layer will not oxidize under high-temperature conditions and has a long service life. It is the preferred positive connection method for high-end high-power car chargers.