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In this lesson, we will talk about the circuit principle and the maintenance of the OLED screen circuit

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Let's take a look at the working conditions of the OLED display

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The first is its power supply,

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the power supply of the OLED screen has 1.8 volts

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What we see here is 1.8 volts

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We have two common types, one starts with VREG,

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such as this VREG_L14A_1P8, which is a 1.8 volt power supply

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In some drawings, it starts with VOUT,

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and most of Huawei use this

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Most of Xiaomi and other mobile phones start with VREG

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This is its 1.8 power supply, or 1.85 volts,

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which is not much different

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This is a power supply

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Let's look at other power supplies

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There is also a 3 volts power supply

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The description of this 3 volts power supply on the circuit diagram usually starts with LCD,

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such as this, LCD_AVDD_3V1, which is 3.1 volts

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On some drawings, its description is VCI_3P0, which is 3 volts

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Let's look at other power supplies

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There is also a power supply called ELVDD, which is 4.6 volts

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It is only 0.3 volts larger than the main power supply

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There is also a power supply called AVDD

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This voltage is 7.6 volts, it belongs to high voltage

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In the drawings, we see that some begin with AMOLED_AVDD,

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it does not express how many volts

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Then there is another power supply,

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which is a negative voltage power supply, called ELVSS, negative 4 volts

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Negative voltage is a kind of power supply,

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which is the power supply of OLED screen

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It has other working conditions

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Its second working condition is reset, RESET

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Then on the common Android phones in our drawings,

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there are more of these two expressions

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One is LCD_RESET_N,

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and the other is commonly used by Huawei, called GPIO_239_LCD_RST_N

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What can we see in this series?

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GPIO is the general-purpose input and output interface of the CPU

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RST represents the reset signal,

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The reset signal is followed by a letter N,

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N means low level active

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The reset on the mobile phone is all with the suffix N

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What is the concept of low level active?

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There are high and low levels in the circuit

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Typically, the highest reset level is 1.8 volts

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In the actual maintenance,

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we should pay attention that if the ground value of this line is normal,

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or there is a voltage of 1.8 volts here,

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then we think there is no problem with this reset

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Okay, this is reset

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That's all for this lesson