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UCD3138: Voice Coil Control

BGX561
Intellectual 610 points
Part Number: UCD3138

TI,

I've only briefly had the opportunity to look through the datasheet for the UCD3138, but it looks like it might be possible to use the PID loop to setup an inner current control loop and an outer position control loop using the EADC frontend for feedback. 

Since the UCD3138 can drive two sets of half bridges, it should be possible to drive a voice coil actuator bidirectionally. 

Before I dive into this, is there a better integrated solution for this purpose with comparable bandwidth (for voice coils) or can you describe why the UCD3138 could not be used for this purpose?

Thanks

  • 0
    TI__Genius 17090 points

    I'm afraid that we haven't looked at the UCD for voice coil control, and we also haven't looked at competing solutions either.   

    The UCD3138 is primarily designed for power supplies, so if you look at the EADC, it has a DAC on one side, essentially a fixed reference point.

    In our PFC code, we do read the 50 or 60 Hertz signal at 50 KHz with an ADC, and put it into the DAC.  Even reading at that frequency, it's a big effort to the the THD at all power levels to meet PFC requirements, let alone audio ones.  The EADC is very fast, but it is only a 6 bit ADC, so it can only look close to the DAC setting.  

    It really doesn't have the dynamic range or the resolution you probably need.  I assume that since you want to control voice coil position, you want high quality audio?

    You might want to look at some kind of TI DSP?

    Of course if you are using the voice coil for some other motion application with less stringent requirements for speed and resolution, the UCD may be perfect for you. 

    I suspect it is less expensive that a full up audio DSP.