• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 50 subscribers
  • Views 573 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

OPA564: output swing

[FAE] Andrew Wang
Genius 10685 points

Part Number: OPA564

Hi team,

Customer is asking if VS- = 0V, VS+ = +9V, non-inverting config with gain = 2, Rf = Ri = 50k ohms, load is over 10Mohms, how closed can output swing to be?

There seems no data to show output swing head room at high impedance output, thx!

Andrew

  • 0
    Guru 324820 points

    Figure 2 shows that the voltage drop becomes almost zero at small currents.

  • 0
    Guru 140200 points

    Hi Andrew,

    figure 2 of datasheet should give an answer to your question:

    Kai

  • 0 in reply to kai klaas69
    TI__Genius 10685 points

    Thanks Kai,

    I know, but I need exact data of either typ or max output swing, customer needs it for putting on the system spec.

    I was expecting the original raw data when plotting this curve, thanks!!

    Andrew

  • 0 in reply to [FAE] Andrew Wang
    TI__Guru* 93105 points

    Andrew,

    As suggested by Clemens and Kai, Figure 2 is the best resource for information about OPA564 Vout performance. It is a Typical Characteristic Curve and an approximation can be interpolated from the Vout curves for the Vs levels shown. 

    TI only assures the electrical performances stated in the Electrical Characteristics table, and for Vout it is specified with VS = ±12V. In each case it is 1 V min. from the supply rail for IOUT +/-0.5 Amps, and 2 V min. from the rail for IOUT +/-1 Amps. TI has not fully characterized or tests the OPA564 with Vs+ = +9 V and Vs- = 0 V and therefore cannot provide any assurances about Vout with that specific supply arrangement.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    TI__Guru 72891 points

    Adding to Tom's comments: OPA564 swing to the rails will be a function of Ron resistance of output transistors, which may be derived from Vout vs Iout curves. Doing so, one may conclude that for 9V supply Ron is between 1 to 2ohm.  Since in customer's non-inverting configuration, with Rin=Rf=50k, the effective load is 100k||10M and there is virtually no Iout, the output swing will be limited by the output stage quiescent current flowing thru Ron output resistor.  Therefore, in the worst case, I would estimate that the output swing to be within 100mV of either rail (50mA*2ohm). 

    Just be aware that this is a non-linear operation (thus, very low AOL and very high Vos) where output voltage is slammed against the rail.

  • 0 in reply to Marek Lis
    TI__Genius 10685 points

    Hi All,

    Thanks a lot for all the feedback!! It's useful.

    Andrew