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What is PNP open collector output?
Open Collector Outputs on Scancon Encoders The characteristic of an open collector output is that the output signal can only be actively pulled to one supply rail (low or high depending on type) by the output transistor, the other state must be pulled up or down passively by a pull-up or pull-down resistor.
How do collector outputs work open?
Instead of outputting a signal of a specific voltage or current, the output signal is applied to the base of an internal NPN transistor whose collector is externalized (open) on a pin of the IC. The emitter of the transistor is connected internally to the ground pin.
How do you wire an open collector output?
To do this, connect an open collector digital output to the control terminal of the relay board, with a 10kΩ resistor pulling the line up to +5V. This way, the relay will be constantly powered until the open collector digital output is switched on, which will then cause the control line to become grounded.
What are the output characteristics of a PNP transistor?
The Output Characteristics Curves for a PNP transistor look very similar to those for an equivalent NPN transistor except that they are rotated by 180o to take account of the reverse polarity voltages and currents, (that is for a PNP transistor, electron current flows out of the base and collector towards the battery).
Do you need a PNP transistor for a NPN sensor?
Instead, manufacturers include an NPN or a PNP transistor to handle higher currents at a sensor’s output. You must ensure that sensors with PNP outputs connect to PNP-compatible controller inputs and NPN outputs connect to NPN-compatible inputs.
When does the NPN transistor turn off, logic-1 is produced?
By adding a pull-up resistor to the NPN open-collector, this pin produces a logic-1 voltage when the NPN transistor turns off. When you have a PNP open-collector connection, it will provide the supply voltage for a logic-1 but it requires a pull-down resistance to produce a valid logic-0 when the transistor turns off.
How are the diodes reversed in a PNP transistor?
Basically, in this type of transistor construction the two diodes are reversed with respect to the NPN type giving a P ositive- N egative- P ositive type of configuration, with the arrow which also defines the Emitter terminal this time pointing inwards in the transistor symbol.