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TPS62826: as an inverter converter, is it possible?

Jeferson Pehls
Expert 1180 points
Part Number: TPS62826
Other Parts Discussed in Thread: TPS62903

Tool/software:

Hello.

I will explain my situation in the design of a current project.

The root power supply is a 1-cell Li-Ion battery, 3.7V nominal, 3V to 4.2V useful range. I'm needing to take this voltage range of the battery to the VIN of 2 DC-DC converters, one with positive output and another with negative output, +2.625V and -2.625V nominal (theoric) [2.625V would be exactly the mid point of 2.5V and 2.75V], both outputs with a current capacity of 1A or more.

For the positive output, I could use the buck converter TPS62826 easily (I believe), and I was wondering if TPS62826, in my case, could be also utilized to generate the negative output of -2.625V @ 1A or more. If this is possible, how the schematic would look like? And, would there be some documentations on this? (if this is possible?). If it's not possible, then I have described my situation, and I would like to ask for Texas Instruments engineers which PNs from TI could fit my need. I think that it would be better (if possible) that for both DC-DC converters (positive and negative) I could use the same chip (same PN), so that my BOM get more reduced and optimized.

Thank you in advance,

Jeferson Pehls.

  • 0
    TI__Mastermind 22700 points

    Hi Jeferson,

    thanks for reaching out in E2E.

    I think in general most of the buck converters can be used in the inverting configuration. But the allowable input voltage range is reduced by the absolute value of the negative VOUT in this configuration. So the maximum allowable VIN of 5.5V for the TPS62826 would be reduced by 2.625V in your case, which results in 2.875V, which is too low for the Li-Ion battery.

    The details of this limitation are explained in section 1.3 of this application note: "Using the TPS6290x in an Inverting Buck – Boost Topology".

    I would suggest to select a converter with a higher VIN range of >7V, such as the TPS62903.

    Best regards,

    Andreas.

  • 0 in reply to Andreas Mueller
    Expert 1180 points

    Hi Andreas.

    Yes, the TPS62903 seems to fit my needs, both for positive and negative outputs, using the same chip PN. I did a check on the datasheet briefly, I need to go deep on it later, and to read the application note that you mentioned. I have a lot ahead, but it seems I found a suitable solution, that's what matter.

    Thank you.

  • 0
    TI__Mastermind 22700 points

    Hi Jeferson,

    thanks a lot for your feedback.

    Feel free to reach out with a new E2E post if you have any questions.

    If you think this thread is solved for now then I would be more than happy if you would click Resolved.

    Thanks and best regards,

    Andreas.