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Hello everyone, today we will learn about the working conditions of the T2 chip in the Apple A2159 circuit

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The working conditions of the T2 chip are all provided by the power chip

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First of all, this PP1V8_ refers to the 1.8V standby power supply

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The PP1V8_ below is also the 1.8V power supply

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There are PP1V1, PP0V82, etc.

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Including T2 core power supply, T2 upper cover memory power supply, and other modules power supply

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Each power supply is generated by PWM control inside the power chip

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For example PPVDDCPU_AWAKE, let's search in the circuit diagram

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This power supply comes from here, its voltage value is 0.625- 1.06V,

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and the maximum output current is 13.4A

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It is output by paralleling 4 inductors here

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These 4 inductors represent that there are 4 PWM circuits inside the power chip

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The bottom 0 ohm resistor is its feedback regulation

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When we drew this timing diagram, we only drew one inductor

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In fact, four inductors work together to generate the power supply

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The same is true for other power supplies,

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some of which are also provided by multiple inductors and multiple PWM circuits

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For example, this PP0V82_SLPDDR is a DDR memory power supply

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Its voltage value is 0.82V and the output current is 6A

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Two inductors are used here, which means that it needs two PWM circuits to provide 0.82V power supply

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There is a 0 ohm feedback resistor at the back end of each PWM inductor

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Each VDD_BUCK here provides the main power supply for each PWM circuit inside

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The various power supplies output by the power supply chip provide working conditions for this T2 chip

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After each power supply is normal,

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the 24M crystal oscillator of T2 starts to work to generate the clock frequency

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The power chip delays to send a reset signal to the COLD_RESET pin of the T2 chip

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After the T2 chip has power supply, clock, and reset,

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it needs to read the program in the SOCROM,

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configure its pins, and start running

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Then, the T2 chip will communicate with the CD3217 through the I2C bus,

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usually through the I2C0 bus

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Before the CD3217 communicates with the T2 chip, it has read the program

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and the Thunderbolt chip has also read the program

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Then CD3217 gets the instruction sent by the T2 chip

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After they communicate with each other, CD3217 communicates with the adapter through the CC bus,

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requesting the adapter to output a power supply that can satisfy the normal operation of the machine

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According to the request of CD3217 and T2 chip,

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the adapter will output a boosted 20V to supply power to the VBUS pin of CD3217

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CD3217 will convert the VBUS power supply

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At this time, PPDCIN_G3H gets 20V power supply

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For this charging chip, AUX_DET is an adapter voltage detection pin

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When it detects that the adapter voltage rises to 20V,

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it will work in the BUCK step-down mode,

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and after the 20V of the adapter is stepped down by PWM,

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a common point voltage of 12V is obtained

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The voltage of the common point is always constant,

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no matter the adapter voltage is 5V or 20V, the common point voltage is always 12V

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Ok, this is the working condition of the T2 chip