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High current occurs when iPhone starts up

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In this video, we mainly explain the fault identification of high startup current

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High startup current actually refers to the current jump when the machine starts up

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In a normal machine, its current jumps from about 80mA

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So if something goes wrong, it will have a current higher than 80mA,

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some of it could be more than 1A,

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or it could be 200/300mA

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According to the size of the startup current,

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the startup current fault can be divided into two types:

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the large startup current and the excessively large startup current

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In the actual maintenance, some people will call it the boot large short

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Boot large short and large startup current are referred to as a fault

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Fault symptom of large startup current

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After the mainboard is powered on, we trigger the switch,

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and the current will jump directly to more than 300mA,

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which is a large current fault

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In the picture, for example,

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when we flip the switch, the current jumps directly to 1.8A

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Let's go to the physical objects to observe the fault phenomenon of large current boot

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Let's take a look at the startup current of a good mainboard

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Once the mainboard is connected to the power cord, we'll trigger the switch

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As you can see, the current starts at about 60mA

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And this current is a normal jump current

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Fault symptom of high current when triggering

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This is a piece of XR mainboard

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After short-connecting, we can find that the current directly becomes about 2A

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Let's look at this 11 mainboard

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After connecting the power cord, we trigger the switch

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After triggering the switch, the current directly reaches 500 mA

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Let's look at this 11 mainboard

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The current jump on this mainboard is also abnormal,

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it goes from 90mA to 500 or 800mA

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This is also trigger high current

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Let's take a look at the iPhone 12 mainboard

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When we trigger the switch, the current jumps directly to 1.8A

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These fault phenomena belong to the trigger high current

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The second type of startup current fault phenomenon

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When the mainboard is energized, we trigger the switch,

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the current will increase instantaneously, and then return to 0

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This belongs to the protection of the power supply

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It's common on Android machines,

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and it's also common on Apple's machines

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Let's look at the current phenomenon of trigger protection

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We can see that after we turn on the switch,

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the current will momentarily reach more than 300mA and then return to 0

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Press the on button again, it jumps again, then goes to 0

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This phenomenon is triggering a large current, and is a power source protection

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Introduction to the fault of excessively large startup current

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When the mainboard is powered on,

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we will trigger the boot and the current will jump from 100 to 300mA

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For example, in the picture, when the mainboard is powered on,

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it triggers the switch, and the current changes from about 200mA

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The starting current of a normal machine is around 80mA

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If the takeoff current is larger than the normal current, about 100 to 300mA,

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it belongs to the excessively startup large current

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Now let's take a look at the real thing

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When the mainboard is powered up, we'll trigger the switch

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After triggering the switch,

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we can see that the current jumps from more than 200 mA

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Then a fault like this would be a high trigger current

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But some machines, when triggered, the current jumps from more than 200mA,

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but the current can still jump up

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This does not affect the system,

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we commonly call it power consumption fast failure

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So that's it for this lesson