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Hello everyone, today we are going to learn about EC standby conditions for ordinary laptops

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This lesson is divided into two parts: introduction to EC and standby conditions of EC

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EC is also called embedded controller,

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it is a single chip microcomputer

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Architecturally, laptop EC and desktop IO are in the same place

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But EC is more powerful than IO

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In the standby state, the EC monitors the battery level, manages the battery charge and discharge,

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and power indicators, and waits for the user to power on

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After it is turned on, it also monitors the temperature information of the system, controls the speed of the fan,

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controls the keyboard and touchpad, controls the power supply of the system, and controls the hibernation state

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EC manages a lot of things

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The EC is referred to as KBC in some circuit diagrams because it contains a keyboard controller

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Common EC package modes include BGA package and QFP package

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And some EC are special, such as the one with Lenovo logo,

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it is special for Lenovo, can not be replaced at will

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EC model identification

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Read the first line of the EC

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For example, this NPCE285UA0DX, it is the model

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When we replace, we need to replace the same model

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If you encounter a dedicated EC, you can replace it not only on the same laptop but also on the same model

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EC standby conditions

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EC standby conditions include standby power supply, standby clock, standby reset and program

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The standby power supply is usually 3.3V,

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and the common names in the circuit diagram are:

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VCC0, VCC1, AVCC, VCCA, VSTBY, etc

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Standby clock is usually provided by 32.768KHz crystal oscillator,

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there are also some EC built-in clock

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Let's take a look at the standby reset

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The standby reset is generated by the standby power supply through the resistor, capacitor,

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or other circuit delay, and the voltage is 3.3V

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Common EC reset names are ECRST#, WRST#, VCC_POR#, or VCC1_PWRGD

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Some ECs are reset internally

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There are two kinds of EC programs

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One exists inside the EC, which we call the EC firmware

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One is in the BIOS chip underneath the EC, which we call the EC ROM

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After the EC meets the requirements of power supply, clock, and reset,

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it needs to read the program and configure its GPIO pin to work properly

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How do you know if an EC comes with its own program?

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We can look at the following four architectures

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First of all, there is a BIOS chip next to the EC, which communicates through the SPI bus

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In this architecture, there is usually no program inside the EC

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Second architecture, there is no BIOS chip next to the EC,

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and a BIOS is connected under the PCH through the SPI bus

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In this architecture, the EC usually has its own program

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The third architecture, PCH and EC connect a BIOS and EC ROM via SPI bus, respectively

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In this architecture, there is usually no program inside the EC

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The fourth architecture, the EC and the PCH share the same BIOS chip through the SPI bus

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In this architecture, there is usually no program inside the EC

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However, a small number of EC will carry a part of the program inside, outside also hang a part of the program

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So this architecture is the most troublesome

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Okay, so that's the standby condition of the EC