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iPhone audio circuit repairing

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This video mainly explains the working principle of iPhone 11 to iPhone 12 ProMax main audio

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11, 12 series main audio circuit works the same

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The main difference from the early models is that

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the 11 and 12 series CPUs will detect the main audio through the I2C bus

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Working principle Step 1,

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when the battery is plugged in or an adjustable power supply is connected,

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the BOOST boost chip will generate PP_VDD_BOOST power supply,

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which will first provide the working voltage for the main audio

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Step 2, after triggering the boot,

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the main power supply will output more than 30 power supplies,

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among which PP1V8_AUDIO, PP1V8_S2 and PP1V2 power supply will provide working voltage for the main audio

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Step 3, after the CPU working condition is normal,

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it will detect the main audio through the I2C bus

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Step 4, during the process of booting into the system,

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when the audio circuit is started, the CPU will send the main clock signal to the main audio

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Step 5, after the CPU sends the clock signal,

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it will send a reset signal to the main audio

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Step 6, after the CPU sends the reset signal,

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it will send the start signal to the main audio

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Step 7, the main audio power supply, the clock signal, reset signal, and start signal are all normal,

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the CPU will detect the main audio again through the SPI bus

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Step 8, when we need the audio circuit to work,

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the main audio will first send an interrupt signal to notify the CPU,

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the CPU will send audio data to the main audio through the I2S bus

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The main audio will perform the codec function, convert the analog signal into a digital signal,

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or convert the digital signal into an analog signal, and then forward it to different circuits

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These signals are the operating conditions of the main audio

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If one is not normal, it will cause the main audio to not work,

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which will cause the entire audio circuit to not work

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That's all for this video