ULN2003A Swiching problem

alanjackson13 said:

I am driving a ULN2003A from two pic outputs. Two 0 -5V 30khz square waves.
I have fed the output from the first driver into the input of the second ie
input pin1 output pin16 is fed into input pin2. And input pin 3 output pin 14 fed to input pin4

The outputs are pulled up to 5v using 10k resistors.

The problem that I have is the putpus drive from 5v to 0.7V. THe output doesn't go down to 0v and I don't understand why?

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WTP Pepper said:

Without even trying to understand what you are aiming to achieve by this odd configuration, the output problem is not Vbe but Vce(sat) of the chip ~0.2V if I have understood correctly.

For a 0v output, you need an N channel FET on the output.

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