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OPA544: OPA544

Michael Ebels
Prodigy 120 points
Part Number: OPA544
Other Parts Discussed in Thread: OPA548, OPA548EVM

I am using the DAC161S055 as a 0 to 5VDC source. I would like to increase the current drive to at least 3A with good 1:1 voltage following. It was suggested that the OPA544 or 548 would be a good choice for that. Are there any application notes or reference designs that relate? Is there an example using sense lines to the load like a bench supply would use?

Thanks, Michael

  • 0
    TI__Guru* 93105 points

    Hi Michael,

    I think the OPA548 would be the better option for the 3 Amp ouput current requirment. It is rated with higher peak output current than the OPA544. You should be able to configure the OPA548 as a unit-gain follower just as you would a low-power operational amplifier providing there isn't some special output load condition. If the OPA548 wil be driving a highly inductive or high capacitance load, then compensation may be needed to keep the circuit stable.

    Since you need input and output voltage ranges of 0 to 5 V, you will need to power the OPA548 with a dual supply (+/-). The supply voltages need to be sufficient such that the input common-mode voltage range and output swing range to the rail are supported. On the other end you don't want to make the supply voltages unnecessarily high, or the power dissipation will be high. For an input range of 0 to 5 V range a supply of +10 V/-5 V would be a good choice, if available.

    There aren't any application notes specific to an OPA548 follower, but the Resistor-Controlled Programmable Power Supply Schematic in datasheet Figure 31 might be a good starting place. The gain would be set to +1 V/V vs the +10 V/V shown. Additonally, the snubber in Fig. 38 Motor Drive Circuit should be included.

    Another useful resource for information regarding application of the OPA548 is the OPA548EVM document. It provides example circuits that may be helpful. You can find it here:

    www.ti.com/.../sbou132.pdf

    Regards, Thomas

    Precision Amplifiers Applications Engineering