Schematic diagram of LM317AG SOT-223 Youshun three terminal voltage regulator

The schematic diagram of LM317AG SOT-223 Youshun three terminal regulator mainly shows its internal circuit structure and working principle. Although it is not possible to directly display specific drawings, they can be described based on their working principles and functional characteristics.

Overview of LM317AG SOT-223 Youshun Three Terminal Voltage Regulator Schematic Diagram
LM317AG is an adjustable voltage regulator with three pins: input terminal (Vin), output terminal (Vout), and adjustment terminal (Adj). It contains an error amplifier, an adjustment transistor (usually an NPN transistor), and various protection circuits inside.

Explanation of key parts of the schematic diagram
Input terminal (Vin):
Receive external DC power input, and the input voltage will be adjusted to the desired output voltage.
Adjustment end (Adj):
By connecting an external resistor network, the desired output voltage can be set. A fixed resistor (R1) and an adjustable resistor (or potentiometer) are usually connected between the adjustment terminal and the output terminal. By adjusting the value of the adjustable resistor, the output voltage can be changed.
Output terminal (Vout):
Provide stable DC output voltage. The value of the output voltage depends on the resistor network connected between the adjustment terminal and the output terminal, as well as the internal circuit of LM317AG.
Internal error amplifier:
Monitor the output voltage and compare it with the internal reference voltage (usually 1.25V). If the output voltage deviates from the set value, the error amplifier will adjust the conductivity of the adjustment tube to restore the stability of the output voltage.
Adjustment tube:
Usually an NPN transistor, connected across the input and output terminals. By adjusting its conductivity, the value of the output voltage can be controlled.
Protection circuit:
Including overcurrent protection, thermal overload protection, etc., to ensure that LM317AG will not be damaged in abnormal situations.
working principle
The working principle of LM317AG is based on a negative feedback circuit. When the output voltage deviates from the set value, the error amplifier will generate an error signal and correct the output voltage by adjusting the conductivity of the regulating tube. By adjusting the value of the external resistor network, the set value of the output voltage can be changed.

matters needing attention
When using LM317AG, it is necessary to ensure that the input voltage is within the allowable range of the device and avoid exceeding its maximum power consumption.
In order to obtain a stable output voltage, appropriate filtering capacitors need to be added to both the input and output terminals.
When outputting high current, attention should be paid to heat dissipation, which can be achieved by adding heat sinks or using fans.
Although it is not possible to directly display the specific schematic diagram, the above description provides an overview of the internal circuit structure and working principle of the LM317AG SOT-223 Youshun three terminal regulator. In practical applications, detailed drawings and circuit parameters in relevant electronic design manuals or data manuals can be referenced for design.