We have been using class AB audio amplifiers for dc-coupled analog servo motor drive for years. Now as we push for much smaller packaging, heat dissipation is a major issue. I have been searching for a 15-20W, BTL, class D solution with ANALOG control input. Can anyone point me to a device/family that might work for this type of application?
Brian,
Please take a look at the TPA3112D1. Let me know if this doesn't make sense for you and we can go from there.
http://www.ti.com/product/tpa3112d1
Ryan Kehr
Motor Drive Application Manager
Ryan,
Thanks. I had tried working my way through the selection guide and ended up with the TPA series which seemed like it would be worth digging into a bit more. I was discouraged though by some of the comments in the audio forum about dc-coupling being a bad idea, and I was not sure how it would affect the bootstrapping, etc.
I have a little concern about the speaker guard technology triggering during normal operation, but since this a servo application, the input signal is likely to be small for long (slow) moves taking longer than the 420ms, and fast moves will involve a polarity change for accel/decel, so I guess that might just work out fine.
Any tips on biasing the input signal to match the 3V expected on the inputs?
Brian
I'll try and ask this another way. How do I correctly dc couple an analog signal that will typically be biased at something like VCC/2. Is there an app note available?
I am really sorry for leading you down the "garden path" here on the analog input audio amplifiers. The input structure will not support a DC coupled input.
I am afraid that there are no parts in the line-up that do.