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Hello everyone, today we are going to learn a typical single PWM controller workflow

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Single PWM controller refers to the chip that can only control 1 PWM output,

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this is called single PWM controller

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For example, this chip model is RT8209,

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and it's made by Richtek

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There are three models: RT8209A, RT8209B, RT8209C

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They have different package modes

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RT8209A has 16 pins and four pins on one side,

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and RT8209B has 14 pins

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Both of these are QFN packages

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However, RT8209C is TSSOP package

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Next, let's take a look at how the chip works

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For this chip to work, it must first meet the power supply

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Here, the VDDP and VDD pins are its power pins

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After the power supply is satisfied, the on signal must be satisfied

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Here, EN is a high level enable signal

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When it gets power and enable signal

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It will output the upper tube drive and lower tube drive pulses

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according to the current set by CS pin and the frequency set by TON pin,

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to control the upper and lower tube conduction in turn, and generate a continuous power supply output

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FB pin is used to detect and adjust its output voltage,

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VOUT pin is used to detect whether the output voltage at the back end of the inductor

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is overvoltage or undervoltage

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When the output voltage is detected to be normal,

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the PG signal output is delayed

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Regarding this PG signal,

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all PWM chips are open-drain outputs and need to be pulled up externally to high levels

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Here the PGND and phase pins are used for current detection

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BOOT pin is used for self-lift voltage and is externally connected to a self-lift voltage capacitor

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When we are repairing the PWM circuit, it is forbidden to remove the chip and add power

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If the PWM chip is removed, the G poles of the upper and lower tubes are in a suspended state

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In this case, power is strictly prohibited

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Since the chip is removed,

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the MOS tube will conduct itself after the upper and lower tube G poles are suspended

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If energized, the high level of the D pole of the upper tube will flow directly to the back end of the inductor,

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which will burn the back circuit of the inductor

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So we in the replacement of PWM chip,

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we can measure the ground value of the G poles of the upper and lower tubes

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If the ground value is infinite, the chip is not welded properly

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Ok, this is the workflow of a single PWM controller