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

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Let's take a look at the startup workflow

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First of all, in the battery circuit,

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a battery positive pole comes out of the battery holder to the charging chip

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The MOS tube in the charging chip is turned on,

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VPH_PWR or VBT_SYS is generated

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This main power supply is transmitted to the power supply chip

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After the power supply chip receives this power supply,

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the clock circuit composed of the crystal oscillator

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and the power supply chip starts to work in standby

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After the power supply works,

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gives a voltage of 1.8 V to the power-on signal line

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The power-on signal line is the line connecting the power-on button

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We press the power button,

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that is, the signal of the power button is artificially grounded

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Pull down the voltage for more than 5 seconds,

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that is, press and hold the power button for more than 5 seconds

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At this time, the power chip will output power to the hard disk,

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CPU, baseband, and temporary storage

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After the power supply is output,

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the power supply will give a clock signal to the CPU,

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and the CPU will give a clock signal to the hard disk

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Clock signal abbreviated as CLK

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Then, the power goes to reset the CPU,

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and the CPU goes to reset the hard disk

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After the hard disk is reset,

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the CPU reads the boot program in the hard disk through the RX and TX communication protocol lines,

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and then performs a self-test on the CPU itself,

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the temporary storage, and the hard disk

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After the self-test is no problem,

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continue to load the system,

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and feed back and output a hold signal PS_HOLD to the power supply,

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and the power supply continues to output power

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Well, this is the boot process of a mobile phone

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Ok, that's it for this lesson