Why use pnp vs npn

PNP transistors. Also, do I have the terminology correct, such as a sourcing sensor connects to a sinking input is a PNP configuration? In the standards, I also wanted to document when to use a pull-up resistor. PNP or other signal issues? Thomas Kolleck, sensor technology engineer, Turck : For the U. PNP sensors are also easier to understand and troubleshoot by technicians, since the sensor will give a high-level voltage signal when the output is active.

If the PNP sensor has integrated thermal, latching, or pulsing short-circuit protection, the existence of a short circuit condition on the load wire will be apparent at the sensor.

In the case of a short to ground in an NPN circuit, there is no abnormal current flow; the load is simply pulled in regardless of the sensor state. This could prove to be somewhat difficult to detect, because if the sensor associated with the grounded load wire is examined, it will be found to have no fault. In the modern industrial world, NPN is considered more common and popular in the Asia-Pacific region simply because of legacy practice and the desire for backward-compatibility.

Nice website and good explanaition, however I still dont know in which situation should I use each other. They have diferences, but why should I use one instead of the other? What do I gain using one or the other? Which one is best? I think it is explained rather well. Trying to use older rate indicators with newer sensors. Just not happening. Kenneth, thank you for your interest in Balluff sensors. Your application sounds very interesting, however, I think we have several different technology solutions to solve this application including capacitive and photoelectrics.

I would suggest that you contact our technical support group to discuss this. Please call us at or email technical. The next question to ask is, what direction do you want the current to flow?

Additional Details: Types of Discrete Electrical Outputs — The majority of sensors used today use Solid-State outputs, not mechanical relays The drawing below shows 2 wires for sensor power and 2 for the switch. Share this:. Email Print. Like this: Like Loading A PNP would go between the voltage source and the load with the other end of the load connected to ground. A more realistic example of the two uses is that involving a load driven by a logic device such as the digital output of an MCU.

Here you can connect one side of the load to 12 V and use an NPN transistor to switch the other side to ground. Conversely, you can connect one side of the load to ground and use a PNP transistor to switch the other side to 12 V. NPN is a common configuration. Almost all open collector outputs are NPN outputs. The benefit of using a PNP is that the load only connects to the source when it is switched on.

In contrast, one side of the load is always connected to the source when an NPN switches it on and off. Most U. And technicians often find PNP sensors easier to understand because the sensor produces a high-level voltage signal when the output is active. A point to note is that some manufacturers label inputs for the corresponding output device rather than for the actual function of the input itself.

An external pull-up resistor could be used to convert an NPN sensor to work with a sinking input.