The Difference Between NPN And PNP

- Jan 07, 2021-

The difference of NPN and PNP

PNP and NPN type sensors actually use the saturation and termination of the transistor to output two states, which are switch type sensors. But the output signal is completely opposite, namely high substitution and substitution. NPN output is zero, PNP output PNP and NPN type sensors generally have three lead wires, namely power line VCC, 0V line, output signal output line.


  1. PNP type

      PNP means that when a signal is triggered, the signal output line out is connected to the power line VCC, which is equivalent to a power line that outputs a high level.

       For the PNP-NO type, when there is no signal trigger, the output line is floating, that is, the VCC power line and the out line are disconnected. When a signal is triggered, it sends out the same voltage as the VCC power line, that is, the out line is connected to the power line VCC, and a high level VCC is output.

       For the PNP-NC type, when there is no signal trigger, it will send out the same voltage as the VCC power line, that is, the out line is connected to the power line VCC, and the high level VCC is output. When a signal is triggered, the output line is suspended, that is, the VCC power line is disconnected from the out line.


2. NPN type

  NPN means that when a signal is triggered, the signal output line out is connected to the 0v line, which is equivalent to output low level, ov.

   For the NPN-NO type, when there is no signal trigger, the output line is floating, that is, the 0v line and the out line are disconnected. When a signal is triggered, the same voltage as OV is sent out, that is, the out line is connected to the 0V line, and the output is low level OV.

   For the NPN-NC type, when there is no signal trigger, it will send out the same voltage as the 0V line, that is, the out line is connected with the 0V line, and the output low level 0V. When a signal is triggered, the output line is suspended, that is, the 0V line is disconnected from the out line.


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                                                PNP Type


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                                                 NPN Type


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