BOB-12009 Functionality

Other Miscellaneous
1

I had a question pertaining to SparkFun Logic Level Converter - Bi-Directional BOB-12009. I have it connected to an FPGA board and a general board for 5V power however I am not seeing the 3.3v signal from the fpga board switch to 5V is there a minimum load needed for this board to work properly?

2

Hello, and thanks for your question.

There is no minimum load to make these work, but the board needs to be powered from the two voltages sources (high voltage and low voltage) that your system is using for it to function. High voltage (5V for example) to the ‘HV’ pin, low voltage (3.3V for example) to ‘LV’, and ground from the system to the ‘GND’ pin.

3

I do that and connect an output pin from the FPGA board to the Channel 1 on the low side, but I’m not reading 5V on the high side.

4
  • - Are you applying a 3.3 volt high to the input on the low side?
  • - Have you tried a different channel to see if the one you're using isn't working?
  • - Is there anything connected to the output?
    • If you can send a photo of your setup, that would be helpful in determining what might be causing trouble.
    5

    Thank you TS-Chris for your assistance,

    I have a 30K load on the output, I have tried different channels same result, and I have a 3.3 high pin on the FPGA powering the convertor.

    Thank You again for your assistance

    6

    Could you please send a photo showing how you have the board connected?

    7

    For convenience Brown, Black, and Blue are ground. I used a multimeter to confirm the voltages between LV and GND and HV and GND are correct. Thank You

    Hookup(S).zip (352 KB)

    8

    It doesn’t look like you have anything soldered and that’s very likely the cause of your issues. Just passing pins or wires through the holes in each board will not work because you won’t have a reliable electrical connection.

    Also, if you’re just converting logic between 3.3 volt and 5 you don’t need those resistors.

    9

    Thank you. It seems that the soldering helped the connections but everything is appearing as active high now with the same set up minus resistors. Any suggestions?

    10

    The output will float high if you’re not actively sending a low to the input. Ground the input and the output will go low.