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High current occurs when iPhone starts up

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In this lesson we mainly explain the power supply IC output power supply search method

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When we repair mobile phones,

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we should first open the circuit diagram, bitmap

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and component map of the corresponding model,

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so that we can easily find it

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Let's take the iPhone 12 Promax as an example

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We first open the circuit diagram, bitmap

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and component map of iPhone 12Promax

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We first find the main power supply in the diagram

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In the circuit diagram, the main power supply is below the CPU

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View the position number of the power IC according to the component map or bitmap

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The main power supply is not marked with a position number in the component map,

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so we need to check it with the help of bitmap

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The power IC is located under the CPU,

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and its position number is U3300

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After finding the position number of the main power supply,

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we will search the position number of the power supply IC in the circuit diagram

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After searching, we can see that there are many search results in the list

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We need to identify

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As long as the position number is inside the box,

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it means that the box is mainly to introduce the power IC

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Something like this is just a marker,

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we don't have to consider it

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The power supply in the drawing will generally be represented by a thick line

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The name BUCK and LDO represent output,

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according to the terms we learned earlier

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On the current page, the right side of the page identifies BUCK0,

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and BUCK0 will have a separate area,

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It means that this block is all the output of BUCK0 power supply

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This set of power supply will be through five inductors,

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and then form a power supply,

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its name is PP_CPU_PCORE

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The diagram also indicates the voltage range of the supply,

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from 0.528V to 1.061V

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Then why do we call it high current?

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We can see that the total current of this circuit can reach 13.8A

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This is just one of the power supplies

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Power IC will output about 15 BUCK power supplies

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And then let's look at this BUCK1

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It is a power supply consisting of three inductors,

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the voltage is between 0.542V and 1.044V,

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and the power supply name is PP GPU

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The power supply is designed for a maximum current of 10A

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From this, we can see that the power supply has a total of 10 BUCKs in this module,

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ranging from 0 to 9

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Let's look at other search results

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Click on the second one, we see that BUCK10, BUCK11,

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BUCK12 and BUCK13 are identified,

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and there are four power supplies

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With the previous 10 power supplies,

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there will be a total of 14 BUCK power supplies with inductors

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The position to the left of this box identifies VDD_BUCK

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VDD_BUCK refers to the power supply input

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Let's keep looking

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The small ones we don't need to look at

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In this power supply module, the one on the left is the power input,

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and the label LDO on the right represents the output

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If you look at its internal logo, there's LDO1 and LDO13

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There is also LDO15, which has a total of 15 power supplies,

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and its sign position is irregular

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Why do we call it a small current supply?

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Because the current output supplied by LDO is relatively small

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We can see that the power supply of LDO1 is 200mA

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and that of LDO7 is 250mA

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That's why it's called a low current supply

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Let's move on

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You can see BUCK3 SWITCHES are powered,

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and this is powered by switches

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Its left side is the input of the power supply,

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the right side is the output of the power supply

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Without this power supply with inductors,

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its current is much smaller,

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generally 700mA, 300mA, or 200mA

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The iPhone 12Promax has a total of 40 power outputs,

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much more than earlier models

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This power supply, how do we measure if it is short-circuited

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We just need to double-click according to the power supply name,

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right-click, click Find bitmap signal

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Any yellow point on the bitmap,

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we can measure the diode value

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The measurement method of each power supply is the same,

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and the same for BUCK power supply

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Double-click the right button and click Find bitmap signal

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We can measure the location of these yellow dots

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In the list, these are just marks, not refers to the power supply,

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we do not need to look up

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In the list, this line is marked as a thin line,

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which belongs to the signal line,

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so there is no need to check this line

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So that's it for this lessons