• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 48 subscribers
  • Views 425 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

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