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DRV2700: Solution for output multiplexing?

David Schwenninger
Prodigy 120 points
Part Number: DRV2700

Hello.

I am using the DRV2700 to drive a piezo pump that has 2 actuators (4 leads) by connecting the 2 actuators in reverse (compared to each other) to the DRV2700 output. The pump actuators are driven with a 1kHz sinus.

I would like to change the connection of the pump from reverse (+- vs -+) to same (both +-) to change the function of the pump to that of a valve. These changes do not have to be faster than 10Hz but at least 1 Hz.

Do you know of a possible solution using solid state?

Best regards,

David

  • 0
    TI__Guru* 84915 points

    Hi, David,

    Excuse me, do you have a diagram that shows the actual connection that you have compared with the connection that you are attempting to do? This is to have a better approach to this issue and determine if it is possible to achieve.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 120 points

    Hi.

    I have made a diagram where the analog multiplexers are represented by switches. I would like this switching to be done by ICs. Maybe 1:3 a mux would be enough.

    VBST is the boost voltage of the DRV 2700. OUT + and OUT- the output to drive

    Best regards,

    David

  • 0 in reply to David Schwenninger
    TI__Guru* 84915 points

    Hi, David,

    Usually, we recommend to take care about the resultant capacitance when more loads are used. However, the frequency that you would like to achieve is too low and the capacitance won't have any negative effect on the output (more details in 9.2.1.2.1 Piezo Load Selection).

    Regarding the first pin connection (VBST), why do you require to connect the loads to the DRV2700 boost voltage?

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 120 points

    Hello.

    Thank you for your reply.

    The connection to VBST - and also to GND - is only required if I want to use one DRV2700 to drive two piezo pumps where only one is active at any time (one to pump in and one to pump out). Setting the inactive pump to VBST would have it act like a closed valve.

    Using two DRV2700 for the two pumps, less switching would be required: each pump lead would require switch selection between OUT+ and OUT- and the rest could be done via the DRV2700 inputs.

    The only feasible way I found to switch the DRV2700 output would be solid state relays for up to 220V AC. With 4 terminals per pump at 2 pumps needing at least 2 switches that would amount to 16 relay switches, which is a bit much.

    Using one DRV2700 per each pump actor (4 in total) would also be a solution.

    What I would like to find out is, if there might be cheaper option with smaller footprint based on a high voltage multiplexer. Or maybe another solution I did not thing about yet.

    Thank you for your help,

    best regards,

    David

  • 0 in reply to David Schwenninger
    TI__Guru* 84915 points

    Hi, David,

    Sorry, I couldn't find any other solution that could fit your application like the DRV2700 and the array that you mentioned. There are other piezo drivers in our Haptics Portfolio ( http://www.ti.com/motor-drivers/actuator-drivers/products.html#p2126=Piezo ), but its output is not as high as the one of the DRV2700. For additional details about the rest of our products, please take a look at the Haptics Portfolio link.

    Please let me know if you have additional questions or comments on this.

    Best regards,
    Luis Fernando Rodríguez S.