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Hello everyone, today we will learn about the boosted circuit of the Apple A2337 adapter

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After the CD3217 and the adapter complete the communication,

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the adapter outputs a boosted 20V power supply

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After the 20V power supply is internally transferred through the CD3217 chip,

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it is directly supplied to the generating circuit of the common point through fuse

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After the 20V voltage is divided by resistors in series,

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the CHGR_AUX_DET signal is generated, which is the adapter voltage detection signal

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When the charging chip detects that the adapter voltage is boosted,

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it will work in the step-down mode,

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and step down the 20V voltage to 12V through PWM to provide power to the common point

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Before the adapter is not boosted, the voltage is 5V

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The charging chip works in boost mode, boosting 5V to 12V

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When the adapter is boosted, the charging chip will step down the 20V voltage to 12V through PWM

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Therefore, the voltage of the common point is always kept at 12V

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This common point power supply can not only charge the battery, but also provide power to the system

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The common point voltage is equal to the battery voltage

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The adapter and battery can provide power to the common point at the same time

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This is the workflow after the adapter is boosted