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TPS7A05: Split power supply design

danielb
Intellectual 270 points
Part Number: TPS7A05
Other Parts Discussed in Thread: TPS7A39

Tool/software:

I am designing a split ±1.65V power supply with a maximum current output of 40 mA to power two op-amps. I could also work with more standard output values such as +-1.5V or +-1.8V. The input voltage is 3.3V. I have identified the TPS7A05 as a potential candidate for generating the positive voltage. Is this a suitable choice?

Additionally, what IC would you recommend for generating the negative voltage? Is there a single IC that can provide both positive and negative voltage outputs?

  • 0
    TI__Expert 6610 points

    Hello,

    Are there any other requirements for the positive and negative rails? Such as IQ, noise, PSRR, or size?

    Typically, TPS7A05 is used in off-battery applications due to its 1uA IQ. Since this application requires both a positive and a negative voltage, TPS7A39 might be a good alternative here.

    Regards,

    Andres

  • 0 in reply to Andres Sagredo
    Intellectual 270 points

    Hi, Andres.

    Thanks for suggesting the TPS7A39. It is an interesting IC. However, it requires a negative voltage input (VINN between - 0.3V or -33V). In our case, we only have 3.3V. Do you suggest any other part?

    Regards,

    Daniel

  • 0 in reply to danielb
    TI__Expert 6610 points

    Hi Daniel,

    There is no LDO which can turn a positive voltage into a negative voltage. So in order to generate the negative voltage it may be necessary to use a charge pump which can invert the voltage. From a quick search this is the first charge pump with inverting voltage that I found: TPS6040

    I heavily recommend asking if this TPS6040 is the best option for generating the negative voltage off of the 3.3 input voltage on a new post. This way the appropriate team can verify the selection.

    For the positive rail if the input 3.3V is not off of a battery then either TPS7A20 for fixed output options or TPS784 for adjustable output would be good selections. If the input 3.3V is from a battery then TPS7A05 would be a good option.

    Regards,

    Andres