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In this lesson, we talk about the channel of the handset signal in the circuit diagram

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This lesson mainly talks about MediaTek, taking Redmi K50 as an example

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You can start to find the earpiece signal of Redmi K50 from J6000

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Open Xinzhizao, find the K series of Xiaomi, and open the schematic diagram of Redmi K50

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To find the signal of the handset, we need to know the code of the handset

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Generally speaking, we can give priority to EAR

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What we have here is the Earphone Microphone, which is the headset

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If there is only the EAR signal alone, it is the earpiece

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Find RCV if you can't find EAR

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We see that RCV is the signal of the earpiece

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Then why do you say this is the earpiece?

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The label "upper SPK" here indicates the speaker on the top

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it's the earpiece and speaker at the top

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Chip U6000 is actually a small audio

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The earpiece of the Redmi K50 is driven by a small audio

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Ordinary earpieces are driven by large audio

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Then why does it rely on small audio?

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Because this earpiece supports high power, it is to play music

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It can also be said that this mobile phone supports dual speakers

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This is the amplified sound signal output to the two contacts J6000 and J6001

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These two contacts are in contact with the earpiece

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Let's take a look at the working conditions of the circuit of the U6000 chip

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First look at its power supply

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Its power supply has VIO18_PMU, 1.8 volts power supply

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VSYS refers to the main power supply

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Its A5 pin and A4 pin are the control signals of the I2C bus

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B2, A2, A1 and B1 pins are I2S3 buses

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This I2S3 bus is the input sound signal

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C1 pin is reset signal

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B5 pin is an interrupt signal

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This chip works like this

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When there is no problem with the control signal and power supply, the sound signal from I2S3 is sent to U6000

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After its internal power amplification, it outputs from the E4 and E6 pins to the contact of the earpiece

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Everyone should pay attention, this arrow is marked wrongly,

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the arrow should be outward, because this signal is output outward

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The Redmi K50 uses a MediaTek processor

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Its earpiece is quite unique

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It also has the function of the top speaker, that is, dual speakers

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It is almost exactly the same as the handset circuit of HiSilicon's Huawei P40

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That's all for this lesson