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Precision current source

Vladimir Laukh
Prodigy 120 points
Other Parts Discussed in Thread: DAC80508, DAC60501, DAC70501, DAC80501, TIDA-01525

Hey!

I'm designing precision current source. I need to supply various DC currents up tp 0.5A with accuracy 0.5% to a load. Load requires 5W maximum power and power dissipation on board should be minimized.
I was wondering if there is off-the-shelf solution for this? I looked at LED drivers, but their datasheets doesn't seem provide accuracy. Or maybe there is a way to estimate achievable current accuracy from specs? Or if there is another product group I should look at?

  • 0
    TI__Guru 53573 points

    Hi Vladimir,

    We current do not sell a current-output DAC that can operate at that high of a current.  We have a new product in development, but you will probably see that available in about 6 months.

    I recommend that you look at this reference design:

    http://www.ti.com/tool/TIDA-01525

    This design uses two discrete opamps to create the current source from a precision DAC output.  You could easily modify this design to support 500mA.  The reference circuit uses a 16-bit, 8-channel DAC80508, but you could consider the DAC80501 if you only need 1 channel.  You could also consider the DAC70501 or DAC60501 if you are okay with lower resolution.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Prodigy 120 points

    Thanks for your time!

    Yeah, that design could do the job.

    However that solution requires variable supply on PVDD to keep voltage drop (and power dissipation) low on MOSFET, due to different loads.

    What about battery charger IC's? Can they provide at least 1% DC current accuracy? Ripple currents doesn't matter in my case, only DC value.

  • 0 in reply to Paul_Frost
    Prodigy 120 points

    Not sure if my answer delivered.

    Thanks for your time! 

    That design could do the job. However, it require variable supply on PVDD to reduce voltage drop (and power dissipation) on MOSFET, cause of varies loads.

    What about battery charger IC's? Can they deliver at least 1% DC current accuracy? Ripple currents don't matter in my case, only DC value.

  • 0 in reply to Vladimir Laukh
    TI__Guru 53573 points

    I am not aware of any battery charging devices that let you set a specific current output.  Did you have one in mind?

  • 0 in reply to Paul_Frost
    Prodigy 120 points

    Hmmm yeah, it doesnt't seem that those IC's are able to provide specific current. I'll stick to that TIDA-01525 design. 

    Thanks for your help!