How to distinguish the positive and negative poles of the power supply of the circuit board?

Printed circuit board, referred to as PCB, is the basic component of electronic components and the connection center. Many people see the dense lines on the circuit board after disassembling the parts, and don’t know how to distinguish the positive and negative electrodes. Then, as a professional in PCB production, the PCB manufacturer Xiaobian will now help you popularize science and how to distinguish the power supply of the circuit board. Positive and negative.

First of all, the pcb editor manufacturer wants to tell everyone that if a designer wants to design a perfect PCB circuit board, the first thing is to determine the positive and negative poles of the circuit board. The designer designs step by step, and considers the matching problem between the individual devices. For DC powered circuits, the power supply is generally divided into single power supply, including power supply positive and power supply ground; dual power supply, including power supply positive and power supply negative. When distinguishing the positive and negative poles in the circuit, the following methods can be used to judge.

1. Determine the positive and negative poles according to the silk screen of the circuit board

When designing a PCB, engineers will use silk screen to mark the pin definitions of the interface part. For the positive and negative poles of the power supply, V+ and GND are generally used to distinguish the positive and negative poles of the power supply. Therefore, first look at the silk screen on the board. You can learn a lot of information through the silk screen on the board. It is very important to correctly understand the silk screen information on the circuit board. As shown in the figure below, V+ represents the positive pole, and GND represents the power ground.

2. Determine the positive and negative poles according to the polarity components

Polar components are polarized and cannot be reversed when used. Commonly used polar components include electrolytic capacitors, diodes, etc. Therefore, the positive and negative poles of the circuit can be determined through polarized components. Taking an electrolytic capacitor as an example, its positive pole must be connected to the positive pole of the power supply, and its negative pole must be connected to GND. Identifying the correct pins of the capacitor can also determine the positive and negative poles of the circuit. The capacitance determines the positive and negative poles as shown in the figure below.

3. Determine the positive and negative electrodes according to the large area of copper pouring

In order to improve the anti-interference ability and reduce the impedance of the ground wire when designing the PCB, the ground will be electrically connected by pouring copper on a large area. If the circuit board is covered with copper, GND is basically used as the network copper pour. It can be judged that the large area of copper is the ground wire.

4. Other ways to confirm the positive and negative poles

You can also confirm the positive and negative poles through the pins of the chip. All chips need power supply and have power supply pins. If you know the pin sequence of the chip, you can also distinguish the positive and negative poles of the power supply. However, this method has a flaw, that is, It is only applicable to the case where there is only one power network. If there are multiple power networks on the circuit board, further confirmation is required through the above methods.