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TPS73HD3: If it works with 2 TPS73HD301 parallel?

Marsh Cai
Expert 3165 points
Part Number: TPS73HD3
Other Parts Discussed in Thread: TPS7A57, TPS7A47,

Hi experts,

Can I parallel two different chips' regulator 2 output to generate a 3.3V output with double output current capability? what about the regulator 1 output, can them be paralleled too?

Thanks,

Marsh.

  • 0
    TI__Mastermind 36525 points

    Hi Marsh,

    You can parallel multiple LDO's using one of 2 techniques: The first technique is ballast resistors, and the second technique is current sense resistors and op-amps.  Ballast resistors will allow you to parallel the LDO's however you cannot obtain exactly 2x the load current as you must account for the current sharing of the LDO's.  If you need 2x the load current then typically you will need 3 parallel LDO's.  The current sense / op-amp technique does not have this limitation but it is more complex to design as you must compensate the op-amp loop on the bench.  We will discuss the ballast resistor technique for now.

    This device is one of our older devices, can you use a more modern device?  For example, the TPS7A57 is our new 5A device with better thermal capability and transient performance than the TPS73HD3, if you can use the TPS7A57 then you may not need to do any paralleling.  If you need higher voltage than the TPS7A57, then can you use the TPS7A47?  That will give you much better performance and if you need more current, the TPS7A47 is much easier to parallel than the TPS73HD3.

    If you need the TPS73HD3, then can you offer some additional details about the application?

    2. What is the total load current that you need?

    3. What is the ambient temperature (25C?)

    4. What is Vin for the 3.3V output?

    5. What is Vin for the 1.8V output?

    6. How much additional voltage drop can your application accept for each rail?  There is some voltage drop across the ballast resistors and we must account for that. 

    Thanks,

    Stephen