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High current occurs when iPhone starts up

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In this video, we mainly explain the common explanations for the startup of high current circuit

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After learning these terms,

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it is convenient for us to find the supply of power output in the circuit diagram

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VLDO, V is actually the voltage

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In the drawings of Apple models,

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LDO refers to the power supply output of small current,

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while BUCK refers to the power supply output of large current

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BUCK1_LX1 and LX2 represent the first and second outputs in BUCK1's power supply

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BUCK_SWI, SWI actually means SWITCHES

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A BUCK_SWI is a high-current switch that converts power supply and also stands for output

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BUCK_FB refers to the power supply feedback of large current

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For example, after the power supply output 1 power supply,

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its voltage is high or low, the power supply IC is unable to identify

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It will go through the output line, and then return to the power supply,

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the power supply IC detects the output voltage

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And the return of the pin position is usually represented by FB

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VDD_BUCK_VDD Indicates power supply

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The VDD_BUCK refers to the power supply input with high current,

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and the VDD_LDO refers to the power supply input with low current

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Let's go to the circuit diagram to identify these terms

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Let's look at the iPhone 12 ProMax circuit diagram

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In the schematic diagram, the U3300 refers to the power IC

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Power supply IC output, according to the term explanation, BUCK stands for power output

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The label BUCK10 here represents the high current supply of the 10th circuit

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This is BUCK11, which is the 11th power supply with high current

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It also consists of two inductors

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This pin, identified as BUCK11_FB, is a feedback to the output power supply

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Its output will be returned to the power supply IC,

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used to regulate the output voltage level

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VLDO represents the power supply output of small current, which has many paths,

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such as LDO1, LDO7, and LDO13

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Why do we label it as a small current?

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We can see that the current supplied by LDO is relatively small

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It's only powered by 50mA

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The power supply is only 150mA

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Why is BUCK called high current power supply?

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As you can see on the label behind it,

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its current can reach 4.2A

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Like this, the current is higher

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In the schematic, we can also see the identifier VDD_BUCK

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VDD_BUCK refers to the power supply input

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The power IC then converts this power supply into different BUCK power supply outputs,

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and then provides the operating voltage to the chip on the mainboard

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As we can see inside the IC block diagram, many will identify VDD_LDO

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VDD_LDO is the input to the LDO power supply,

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which is converted to the LDO power supply

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In the drawings, we can also see SWITCHES, labeled here as BUCK3 SWITCHES

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It's actually called a BUCK_SWI, and it's a switch power supply

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The left side is the power supply input of the module,

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and the right side is the power supply output of the module

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So that's it for this lesson