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OPA244 OPA379 output current

Atsushi Okui
Genius 4015 points
Other Parts Discussed in Thread: OPA379, OPA244

Hello, all

Now we are considering to use OPA244 or OPA379 for our next model.

I am referring each datasheet, but I could not find out find out the output current information when applying Vcc=3.3V.

We need at least 0.4mA on this condition.

Would you please let me clarify whether OPA244 or OPA379 could output at least 0.4mA when applying Vcc=3.3V?

Thank you in advance for your information.

Best regards,

  • 0
    TI__Guru* 93105 points

    Hello Okui-san,

    I reviewed the OPA244 and OPA379 data sheets looking for indications of how the output current may perform with a single +3.3 V supply. The OPA379 data sheet does have an Output Voltage vs. Output Current graph in Fig. 6. And although it was developed with Vs of +/-2.5 V (5 V), the output current performance will not be significantly different with a V+ equal to +3.3 V. That graph shows the OPA379 output current levels approaching 10 mA - depending on temperature which is a good indication that it has high output current drive relative to its low operating current. Also, I tested the OPA379 simulation model output current drive with V+ of +3.3 V. It is a sophisticated model that includes output current characteristics and it produced a maximum output current of about +/-7 mA. Therefore, it appears the OPA379 will easily provide 400 uA, and more, output current. It has the added benefit of a rail-to-rail input common-mode voltage range.

    It is a little harder to determine if the OPA244  will provide the 400 uA with V+ of 3.3V. The Output Voltage Swing vs. Output Current graph shown on data sheet Pg. 6 was established with +/-15 V supplies. That is much higher than a single 3.3 V supply and the drive capability typically does fall off with lower supply level for most operational amplifiers. My thought is that it will still be able to supply a couple of milliamperes with V+ set down to 3.3 V. The OPA244 has a simpler simulation model and its output current characteristics are not as developed as the OPA379 so it is difficult to use it as a gauge. Some points to keep in mind from the data sheet are the positive input common-mode voltage and positive output swing are limited to about (V+)-0.9 V for the OPA244. Therefore, with V+ of 3.3 V the positive output swing would be limited to about +2.4 V.

    It does appear that the OPA379 is the clear choice providing all of its other specifications meet the application requirements.

    Regards, Thomas

    PA - Linear Applications Engineering