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TPS61091: For low power application?

ArTzy
Genius 16460 points
Part Number: TPS61091

Hi Experts,

Good day. Asking your assistance on this query:

We have a problem with the TPS61091 component. We are using it in an application designed to be Low power that works at 3.3V powered by 2 AA batteries. The step-up aims to regulate the power supply so that it is always 3.3V.

The problem comes when the module goes into deep sleep. The consumption of the equipment powered by the boost is 3mA, if we skip the boost and feed directly from the battery it consumes 40uA. Attached is the schematic of the configuration.

As we have seen, for the device to enter "Power Safe mode", port 10 'sync' must be set to Gnd.

Is there a configuration problem? Is the module suitable for a low-power application?

Thanks for your help.

Regards,
Archie A.

  • 0
    TI__Mastermind 24260 points

    Hi Archie,

    Thanks for reaching out on E2E.

    The schematic is ok. What will happen when device goes into deep sleep?

    Can you take the waveforms of Vin, Vout, SW and iL when the boost consumes 3mA?

    Regards,

    Bryce

  • 0 in reply to Bryce Xun
    TI__Genius 16460 points

    Hello Bryce,

    We attached here a document where you'll be able to see the waveforms and the right schematic and performance of our circuit.

    For your assistance.

    Thank you.

    Regards,
    Archie A.

    Power consumtion TPS61091.pdf

  • 0 in reply to ArTzy
    TI__Mastermind 24260 points

    Hi Archie,

    Thanks for your waveforms.

    I think the inductor value is too large than our recommended, may I know your calculation equations? Would you try with 6.8uH inductor and test the current with digital-multimeter? The inductor ripple may also have effect on the efficiency.

    I have one question, is the load current the same with different voltage 3.0V, 3.3V? What is the output current value when the load is connected with 3.3V?

    Regards,

    Bryce

  • 0 in reply to Bryce Xun
    TI__Genius 16460 points

    Hello Bryce,

    Thanks for your guidance.

    Here I attach you an excel with the equation calculations. We Tried with an 6.8uH inductor, but we didn't appreciate much difference.

    We also tried with different input voltages but there are just slight differences.

    Alkaline 2,62V: 3,02mA
    Alkaline 2,83V: 2,79mA
    External power supply 3,16V: 2,6mA

    Regards,
    Archie A.

    inductor value.xls

  • 0 in reply to ArTzy
    TI__Mastermind 24260 points

    Hi Archie,

    Thank you for your reply. I will reply to your question next Monday.

    Regards,

    Bryce

  • 0 in reply to Bryce Xun
    TI__Genius 16460 points

    Thanks, Bryce.

    Looking forward for your response.

    Regards,
    Archie A.

  • 0 in reply to ArTzy
    TI__Mastermind 24260 points

    Hi Archie,

    Thanks for your feedback.

    The inductor calculation formula is based on continuous conduction mode. So the result is not applicable in light load situation. For more details, you can refer to the following Application Note.

     

    If inductor value is too large, in power save mode, only when the peak inductor current reaches the target value, the device stops switching. From the waveforms of SW, the long time continuous switching can be observed. So the efficiency is low. Can you also forward the waveforms of iL,SW, Vin, Vout when inductor has changed to 6.8uH?

    Regards,

    Bryce