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SN6505A: Unbalanced load when bipolar output

Shota Mago
Expert 6580 points
Part Number: SN6505A

Hi team,

My customer considers to use SN6505A and provided some questions.

  1. Is it okay to have unbalanced load when bipolar output configuration like Figure.48?
    e.g. For Positive supply side: 300mA
           For Minus supply side: 20mA
  2. Could you provide start-up waveform if you have?
    The customer would like to know inrush current waveform.

Best regards,

Shota Mago

  • 0
    TI__Genius 17100 points

    Hi Mago-san,

    1. It is recommended to balance loads for all SN6505 output conditions, but the balance is in terms of power. What are the positive and negative output supply voltages?

    2. A startup waveform for a 5Ω, 10uF load:



      These waveforms do not include a current measurement, but since the SN6505 has integrated soft start and internal current limiting, current transients during startup are safe for the device. Exact inrush current values vary system-to-system (based mostly on load capacitance) and are not expected to exceed SN6505's current clamp limits of 1.42A - 2.15A.

      If inrush current should be reduced, using an inductor as described in the final post of this thread might be helpful.


    I look forward to your response.


    Respectfully,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Expert 6580 points

    Hi Maunel-san

    Thank you for your quick response.

    In terms of unbalanced load, please refer to attached block diagram.

    ±5V powers op-amps.

    But positive supply side also powers some digital devices so unbalanced load condition is inevitable.

    What should the customer do to deal with this condition?

    Best regards,

    Shota Mago

  • 0 in reply to Shota Mago
    TI__Genius 17100 points

    Hi Mago-san,

    Thank you for including the information above and a block diagram. Since these supplies are derived using a full-bridge rectifier, each current component is split evenly between both halves of the transformer, so load-balancing issues are not expected in this system.


    Best,
    Manuel Chavez