High current occurs when iPhone starts up

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

When we repair mobile phones,

we should first open the circuit diagram, bitmap

and component map of the corresponding model,

so that we can easily find it

Let's take the iPhone 12 Promax as an example

We first open the circuit diagram, bitmap

and component map of iPhone 12Promax

We first find the main power supply in the diagram

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

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

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

so we need to check it with the help of bitmap

The power IC is located under the CPU,

and its position number is U3300

After finding the position number of the main power supply,

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

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

We need to identify

As long as the position number is inside the box,

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

Something like this is just a marker,

we don't have to consider it

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

The name BUCK and LDO represent output,

according to the terms we learned earlier

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

and BUCK0 will have a separate area,

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

This set of power supply will be through five inductors,

and then form a power supply,

its name is PP_CPU_PCORE

The diagram also indicates the voltage range of the supply,

from 0.528V to 1.061V

Then why do we call it high current?

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

This is just one of the power supplies

Power IC will output about 15 BUCK power supplies

And then let's look at this BUCK1

It is a power supply consisting of three inductors,

the voltage is between 0.542V and 1.044V,

and the power supply name is PP GPU

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

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

ranging from 0 to 9

Let's look at other search results

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

BUCK12 and BUCK13 are identified,

and there are four power supplies

With the previous 10 power supplies,

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

The position to the left of this box identifies VDD_BUCK

VDD_BUCK refers to the power supply input

Let's keep looking

The small ones we don't need to look at

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

and the label LDO on the right represents the output

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

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

and its sign position is irregular

Why do we call it a small current supply?

Because the current output supplied by LDO is relatively small

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

and that of LDO7 is 250mA

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

Let's move on

You can see BUCK3 SWITCHES are powered,

and this is powered by switches

Its left side is the input of the power supply,

the right side is the output of the power supply

Without this power supply with inductors,

its current is much smaller,

generally 700mA, 300mA, or 200mA

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

much more than earlier models

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

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

right-click, click Find bitmap signal

Any yellow point on the bitmap,

we can measure the diode value

The measurement method of each power supply is the same,

and the same for BUCK power supply

Double-click the right button and click Find bitmap signal

We can measure the location of these yellow dots

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

we do not need to look up

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

which belongs to the signal line,

so there is no need to check this line

So that's it for this lessons