• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 47 subscribers
  • Views 861 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.

OPA544T

Ronnie Adkins
Prodigy 90 points

Other Parts Discussed in Thread: OPA544, OPA547, OPA569, DRV104

Hi, 

I'm using a OPA544T to drive a valve. Now, the OpAmp circuit is a Non-inverting circuit, with R1 = 10k and R2 = 22k. With the resistor naming as in the data sheet. Although its a really simple circuit it won't work. On no load, the output follows the input and when I connect the valve, the output stays at zero. What could be the reason, is it that the chip has burnt?

Ronnie

  • 0
    TI__Guru* 93105 points

    Hello Ronnie,

    Your application sounds straightforward enough as an amplifier assuming the power supply setup is correct. If the output cannot drive the actuator it may be damaged. You do have to be mindful about the possibility of an inductive load - such as the actuator - generating a potentially damaging back EMF. A back EMF can produce an output terminal voltage the results in the amplifier's output transistors being biased in a manner where they conduct excessive current and become damaged.

    The OPA544 data sheet, Figure 4, shows output protection for motors, actuators, etc. Applying this protection should keep the OPA544 safe from back EMF.

    Regards, Thomas

    PA - Linear Applications Engineering

     

  • 0 in reply to Thomas Kuehl
    Prodigy 90 points

    Hi Thomas,

    About the power supply I've connected V+ to 12 and V- to 0. I'm guessing that's alright? I've sorta bent the pins of the chip to solder it onto the board, hopefully that wouldn't have caused any damage. 

    Would you happen to know any other OpAmp that can supply .5 amps?

    Ronnie

  • 0 in reply to Ronnie Adkins
    TI__Guru* 93105 points

    Ronnie,

    There lies the problem; the OPA544 is a dual supply operational amplifier, with a minimum supply of +/-10 V. A single +12 V supply will not work. Take a look at the OPA547:

    http://www.ti.com/lit/ds/symlink/opa547.pdf

    And the OPA569:

    http://www.ti.com/lit/ds/sbos264a/sbos264a.pdf

    These are useable with a single supply and an input common-mode level to 0 V. Make sure the output level swings low enough to meet the application requirements.

    When it comes to driving actuators we have an interesting family of drivers specifically designed for that application. Take a look at out DRV101 through DRV104 drivers:

    http://www.ti.com/product/drv101

    You may find this is a more suitable, more efficient solution.

    Regards, Thomas

    PA - Linear Applications Engineering

     

     

     

  • 0 in reply to Thomas Kuehl
    Prodigy 90 points

    Hi Thomas, 

    Thanks for your reply! Yes, that could be it. Well the problem is that I need to be able to go from 0 to 12 volts (as I'm controlling a proportionate valve)with a current rating of 0.5 amps and would need it in  a through hole package. 

    Apart from the OPA544T, I couldn't find anything more appropriate.

    Ronnie 

  • 0 in reply to Ronnie Adkins
    TI__Guru* 93105 points

    Hi Ronnie,

    The OPA547 that I mentioned is available in a stagger-formed, 7-pin, TO-220 (T) package and is intended for through-hole assembly.

    Also, I came across this EDN application circuit for a actuator driver. You might get some ideas from it:

    http://electronicdesign.com/power/smart-solenoid-driver-reduces-power-loss

    Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 90 points

    Hi Thomas, 

    Thanks for the help. I think I'd go with that!

    Cheers!

    Ronnie