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OPA569 as Voice coil drtiver

Chintan Bhatt
Prodigy 70 points
Other Parts Discussed in Thread: OPA569, TINA-TI

i am planning to use OPA569 as a voice coil driver. my driving current requirement is just 250mA. so first question can i design a circuit with OPA569 which source only 250mA current? second question is that, i have come across a design on TI called "Bridge Tied Load (BTL) V-I Converter" which used OPA569 only. can i use the same design to drive my voice coil actuator with 250mA current source? if yes then i can straight away use this design for my prototype development.

your quick help will be appreciated

thanks you 

  • 0
    TI__Guru* 93105 points

    Hi Chintan,

    Let me address your OPA569 questions:

    • "My driving current requirement is just 250 mA... can I design a circuit with OPA569 which source only 250mA current?"
      • The OPA569 can readily source 250 mA. Running it at current well below its 2 Amp maximum can make the thermal management much easier. 
    •  "I have come across a design on TI called "Bridge Tied Load (BTL) V-I Converter" which used OPA569only. Can I use the same design to drive my voice coil actuator with 250mA current source?"
      • You should be able to apply the TI Precision Design, SLAU503, to your voice coil application. However, be aware that your load not only has a resistive element, but reactive as well. That might lead to instability and result in oscillation. If that proves to be the case, then the circuit compensation will require evaluation and correction. Here's the link to the TI Precision Design, "5% Error, 0.5-4.5 V Input, +/-2 A Output, Bridge-Tied-Load (BTL) Voltage-to-Current (V-I) Converter:"

    Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 70 points
    Hi Thomas,

    thanks for your reply, really appreciate your input. i tried the TINA-TI schematic simulation by replacing resistor with Inductor and tried running it. simulation results does not show any instability. but i do not know if there is any practical implications with voice coil actuator. so, if you have any kind of doubt about the possibility of instability then suggest a possible modification so that i can implement it before i go for PCB fabrication.

    your suggestions will be very helpful.

    thanks you with best regards

    Chintan
  • 0 in reply to Chintan Bhatt
    TI__Guru* 93105 points

    Hello Chintan,

    I expect the voice coil impedance will be different from that of the load used in the original TI Precision Design circuit. However, in slau503, sections 3.4 and 3.5, it is clear that the referenced components are for compensation purposes. Hopefully, if there is a stability issue when you construct your circuit it can be resolved by adjusting these components. Make sure you include positions for them on your PC board layout.

    Regards, Thomas

    PA - Linear Applications Engineering