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ADP5070 output mismatch

Category: Hardware
Product Number: ADP5070

Hi,

I have designed below schematics for ADP5070 to work with Vin = 5V and Vpos = 2,49V  Vneg = -2,51V.
Somehow it does give totally wrong values like Vpos = 4V and Vneg = - 6V. Is there something wrong with feedback resistor values?
I have made layout according to datasheet guidelines.

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  • Hi,

    Thanks for the update. I was just going to ask that why my calculations gave -5V but here´s the reason. I have tried to update buck/boost implementation to SEPIC one but sometimes it gives +2,5V and -4,3V in witch the negative voltage FB2 pin gives 0,4V. This should be 0,8V but I don´t get the root cause for this yet. Any idea where to look issues?

  • Hi, 

    Can you try to check the switching frequency waveform and the duty cycle first? If both parameters are normal, then I would assume that there is something wrong with the values of your feedback resistors.

    Also, try to check what happens to the output voltage if you put the negative rail in light load. Would be great if you could give me startup waveforms during light load and full load.

    Let me know the results. Thank you. 

    Regards, 

    Fritz Cyrill Gonzales