Another alternative for >5V DIO logic?

3 posts / 0 new

Fri, 05/25/2018 - 17:05

#1

mikelwrnc

mikelwrnc's picture

Another alternative for >5V DIO logic?

I'm looking to toggle an npn transistor with 5v on the collector (emitter connected to an LED then ground). I've seen the options here but would it work to simply connect two DIOs to the base pin, providing a sum of 6.6V and causing the npn to open all the way when both DIOs are set to high?

Tue, 05/29/2018 - 11:31

#2

LabJack Support

The DIOs can not be operated

The DIOs can not be operated in series like that. Here are a few options for driving the LEDs:

Use an NPN on the cathode side of the LED. In this configuration the LED will be connected to the collector and the emitter will be connected to ground. The base then just needs a resistor to the digial IO on the Labjack. Keep in mind there is some impedance on the line already.
Use a PNP on the anode side of the LED. In this case the emitter will connect to Vs and the collect to the LED. To switch the LED on set the digital IO to output low. To switch the LED off set the digital IO to input.
Depending on the LEDs you are using and number of them that will diving at any given time it may be possible to drive them directly from the digital IOs.

Wed, 05/30/2018 - 00:12

#3

LabJack Support

https://labjack.com/support

https://labjack.com/support/app-notes/driving-leds

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