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In this lesson, we talk about the circuits related to the trigger small current

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In the previous lesson we learned about the boot process

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Now let's take a look at what these terms mean

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VBAT refers to the positive pole of the battery,

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the negative pole is usually not shown on the block diagram

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Each chip has a ground wire, which is the negative pole

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The power chip, crystal oscillator,

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hard disk on the boot base, CPU, temporary storage,

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and other chips all have ground wires,

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but they are not marked in the block diagram

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Let's take a look at what these terms mean

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The MOS tube on this charging chip only acts as a switch,

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here is generally a PMOS tube,

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which is a P-channel MOS tube, which is used as a switch

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VPH_PWR is the main power supply

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This is a crystal oscillator with a frequency of 38.4MHz

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This is the power chip

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PWRON is the power-on signal

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What about KYPD_PWR? It is also a boot signal

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Xiaomi's boot signal is called PHONE_ON_N

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There are some other power-on signals are called KEYPD_PWR

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The power-on signal line has a variety of English references,

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This is the power button

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Where is the power button? It's on a seat,

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generally leading to a seat or a shrapnel

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Usually the socket it is attached to is called a boot socket

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This is a power supply,

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the power supply output to the power supply is not marked with its exact code

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In the drawing, the power supply starts with VREG or VOUT,

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or the chip pin output is VDD, VCC,

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generally the power supply starts with the letter V

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In the drawing, its expression may be VREG_UFS_3P0,

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and 3P0 represents the power supply of 3V

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There are a lot of power supply codes,

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because there are many brands of Android phones

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For example, VBUCK is also a common power supply

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These terms in the drawings all indicate power supply

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The CPU power supply is abbreviated as CORE,

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which refers to the power supply of the CPU core

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Of course, there are many ways for its power supply,

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including GPU, modem power supply

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This is just a rough reference

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In fact, there are as many as 20 to 30 power supplies for Android phones

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There is no way to label them one by one

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All we need to know is that on Android,

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there are about 20 to 30 power lines for the CPU,

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for the memory, for the hard drive

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CLK is the clock signal

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This is the reset signal

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This is a hold signal

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Similarly, this one is reset, sometimes abbreviated as RST

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This is CLK, the clock signal

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RX is receive, TX is transmit

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Here is a whole process of trigger small current at startup

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Okay, that's it for this lesson