Low voltage control (ULN2003A )

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Jack Xiu

Joined Jan 18, 2018
1
I have a project. To get an output of +12V for High or 0V for Low, the maximum current is 25mA. As tm4C123 can output 5V or 3.3V and small current. I choose ULN2003. Could anyone have such experiences on the wiring please?
upload_2018-1-18_7-21-33.png
 

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ericgibbs

Joined Jan 29, 2010
13,251
hi Jack,
Welcome to AAC.

The ULN2003 is an Inverter, so for +5V input you will see a close to 0V output, like wise a 0V will give a +12V output when using a 12V supply.
E

EDIT:
You could consider a UDN2981
 

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ElectricSpidey

Joined Dec 2, 2017
1,762
Yea, the ULN2003 can’t source current, only sink.

AKA can't output +12 volts. (open collector NPN Darlington)

If you choose the UDN2981, be sure to use a reputable source because they are obsolete, and there are counterfeits on the market.
 

GopherT

Joined Nov 23, 2012
8,012
I have a project. To get an output of +12V for High or 0V for Low, the maximum current is 25mA. As tm4C123 can output 5V or 3.3V and small current. I choose ULN2003. Could anyone have such experiences on the wiring please?
If you are connecting to an INPUT logic of your DEVICE, you need to add a resistor from the UNL2003A to a 12V supply (1k to 10k is typical and depends on the speed, input capacitance and impendence of your DEVICE. Then, connect your DEVICE to the node between resistor and ULN2003A. As said above, the output will be inverted. If an inverted signal does not work for you, run it through an open block on the UNL2003A to invert it again (resistor to +12 on each is needed).

If you are driving (powering) the DEVICE, then you can just connect the (-) of DEVICE to an output pin (collector) of the ULN2003A and the (+) of DEVICE to 12V.
 

AnalogKid

Joined Aug 1, 2013
9,290
What is "my device"? What is its power source? How much current will it draw at the input you show?

Without more information, all responsess are guesses, not answers.

ak
 

ElectricSpidey

Joined Dec 2, 2017
1,762
I would have to assume (bad idea?) his device is the tm4C123, and remember he is using right to left on his diagram.

And I would imagine the area with the question mark could be replaced with simple logic inverters.

But yup…all guesses.


Well…looking at it again his diagram does not match the text.
 
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