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Buck Converter UC3573 not working

Katleen Miguel
Prodigy 20 points
Other Parts Discussed in Thread: UC3573, TPS54320, TPS54227, TPS54228

I'm building a Buck Converter using TI's UC3573 (www.ti.com.cn/.../uc3573.pdf), 10-15V input, 5V 2A output. However, it doesn't convert. AT ALL. The output voltage and input voltage are basically the same. Here's the schematic:

Output inductor is 100 uH.

Output capacitor is 660 uF.

Switching frequency is 100 kHz.

Is there something that I missed? My calculations check out. 

  • 0
    TI__Guru**** 191445 points
    You probably did not pick a particularly good IC for your application. Any reason why you chose UC3573? we have lots of more modern ICs with more application support such as detailed design procedures, automated tools such as webench etc.

    Does your circuit switch at all at the catch diode cathode? What about your compensation components?
  • 0 in reply to JohnTucker
    Prodigy 20 points
    UC3573's application design is pretty straightforward and very simple. I took an easy way out. The voltage is pretty much the same all throughout the components. No converting is done. The inductor and MOSFET doesn't even heat up. Any IC recommendations?
  • 0 in reply to Katleen Miguel
    TI__Guru**** 191445 points
    TPS54320, TPS54227, TPS54228 come to mind immediately. There are many others. If you can post some waveforms of your present circuit, I can take a look. Did you build it on a pcb? Sometimes there are layout issues.