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UA78M-Q1: UA78M-Q1

harsh purohit
Prodigy 100 points
Part Number: UA78M-Q1

hey,

I'm using this UA78M-Q1 IC to generate -3.3V but I'm not getting anything at output why? here I'm sharing a schematic of how I configure it to get -3.3V please let me know that I'm really able to generate -3.3V using this IC, because I already generated -3V by same configuration using IC LP2950ACZ I'm also sharing a schematic of it.

https://e2e.ti.com/resized-image/__size/320x240/__key/communityserver-components-multipleuploadfilemanager/b01b0314_2DUsing UA78M-Q100_0a15_2D00_4df1_2D00_ba8d_2D00_4d00ca292c0b-560533-complete/a.PNG

  • 0
    TI__Expert 6640 points

    Hi Harsh,

    Thanks for reaching out. First, let me clarify a few things on your schematic.

    What are connections "1" and "2" on the far left of the schematic? It looks like "1" is -3.3V, can you please confirm?

    Also, what is the reason for using large non-ceramic capacitors, as well as a mix of ceramic and non-ceramic caps?

    Regards,

    Kelsey

  • 0 in reply to Kelsey Farr
    TI__Expert 6640 points

    Hi Harsh,

    I looked at this with my team, and from what we can read on the schematic, we think this generally should work. So, the issue may be stemming from the input to output voltage differential. 

    If you could please help clarify connections "1" and "2" on the left side of the schematic so I can check if those may be causing any issue. Also, you mentioned you're not getting anything at the output -- does that mean you're seeing 0V at the LDO output? Are there any waveforms you're able to share?

    Regards,

    Kelsey