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OPA2381: Sinking Current Capability

Jejomar Ildefonso
Expert 8590 points
Part Number: OPA2381

Hi Team,

The OPA2381 datasheet shows its output current of 10mA. Is the device capable of sourcing as well as sinking this output current spec? Thanks in advance!


Kind Regards,

Jejomar

  • 0
    Guru 140200 points

    Hi Jejomar,

    this mainly depends on the supply voltage:

    Kai

  • 0
    TI__Guru 60610 points

    What the OPA2381 Output Swing vs Iout graphs show is that on 5.5V total supply it can sink and source 10mA with the output within 1V and 600mV of the rails, respectively.

    On 2.7V total supply (+/-1.35V), OPA2381 can source 10mA with output within 1V below (V+) BUT it cannot sink 10mA current (max 7mA at 25C).

  • 0 in reply to Marek Lis
    TI__Expert 8590 points

    Hello Marek and Kai,

    Thanks for looking into this. In our customer's application the OPA2381 is supplied with +2.5V and -2.5V.

    But let's assume this would be +2.75V and -2.75V. Then it could sink up to 10mA if output voltage is between +1.75V and -1.75V. And it could source up to 10mA when output voltage is between 2.15V and -2.15V. Are we correct?


    Kind Regards,

    Jejomar

  • +1 in reply to Jejomar Ildefonso
    TI__Guru 60610 points

    Jejomar,

    The graphs in OPA2381 datasheet were generated with load connected between Vout and mid-supply (ground).  Thus, what you say is true for as long as in the case of sourcing current the other side of the load resistor is connected to a voltage below Vout while in the case of sinking the load is connected to voltage above Vout.

    Having said that, please be aware that since OPA2381 input common-mode voltage range is specified only between (V-) < Vcm < (V+) -1.8V ( see below), the input could be the limiting factor and therefore, you could not achieve 600mV output swing to positive rail using a follower (G=1) configuration.