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TPS65135: Using TPS65135 with Unbalanced Loads

Jory Olson
Prodigy 120 points
Part Number: TPS65135
Other Parts Discussed in Thread: TPS65130

I need to create +5V @ 45mA and -5V at 2mA for an analog signal processing circuit.  The datasheet for TPS65135RTER says that it is designed for balanced loads such as AMOLED drivers.  What happens if the loads are not balanced?  I can probably live with poor voltage tolerance, but might have a problem with poor load regulation.  I have been unable to find a simulation tool for this part.  Please advise.  

  • 0
    TI__Mastermind 18550 points

    Hello Jory,

    TPS65135 is not recommended where there is more than 50% current mismatch between positive and negative rail load. With higher current mismatch, regulation and stability issues can occur.

    I would suggest to consider either TPS65130 or TPS65132B0 for your application. These devices can support 100% load mismatch between positive and negative rails.

    Kind Regards,

    Liaqat

  • 0 in reply to Liaqat Khan
    Prodigy 120 points

    Asked about the behavior of the TPS65135 when the load is imbalanced by more than 50%.  I understand this is not recommended, but I would like to know what happens. 

  • 0 in reply to Jory Olson
    TI__Mastermind 18550 points

    I think in my response I mentioned that " With higher current mismatch, regulation and stability issues can occur".

    Below is more information directly from the datasheet that says that for larger current mismatch, output goes out of regulation and device shuts down.

    ======

    7.3.7 Output-Current Mismatch The device operates best when the current of the positive output is similar to the current of the negative output. However, the device is able to regulate an output current mismatch of up to 50% (See Figure 26 for typically allowed currents, only 50% mismatch is specified). If the output-current mismatch becomes much larger one of the outputs goes out of regulation and finally the device shuts down. In case of zero load of one output the other output can support up to 5 mA. The device automatically recovers when the mismatch is reduced. The formula below can be used to calculate the maximum supported current mismatch.

    =======

    Kind Regards,

    Liaqat