Having issues with a ‘high’ voltage level shifter I am creating
Posted: 02 January 2018 02:20 AM   [ Ignore ]
Jr. Member
Total Posts:  1
Joined  2018-01-02

I am having issues with a ‘high’ voltage level shifter I am creating. I need to drive a 28Vpp waveform with specific timings ( <.1us rise time, 1us pulse width), converting from the 3.3V logic that comes out of my microprocessor. I currently have the circuit below:

Which produces the following waveform:

Great! However, I will need to need drive a fairly long cable. When I add 100pf of capacitance to the output:

I get the following waveform:

This waveform doesn’t meet my requirements of having a rise time of less than 0.1us. What can I do to overcome this? I have tried replacing the transistor based circuit with an LM139(http://www.kynix.com/Detail/861098/LM139.html) comparator, but that was still susceptible to capacitance. Are there ICs available that could fix my issue? I can handle about 4us of prop delay if needed. Thanks!

Posted: 02 January 2018 11:30 AM   [ Ignore ]   [ # 1 ]
Sr. Member
Total Posts:  4523
Joined  2009-10-21

This is not that kind of site. You might get an answer. But mostly we discuss issues of science and technology, not details of actual science.