Electronics > Projects, Designs, and Technical Stuff
Boost converter- dynamic output
PurvR:
Hey everyone I am building a DIY speaker powered by batteries. I'm using lithium Ion battery and boosting the voltage to 12 volt using xl6009 boost converter. The amplifier is 10 watt class d amp and works form voltage range of 7 volts to 15 volts. I was wondering if the boost converter can be modified to change the output voltage according to increase in load as the volume increases, like as I increase the volume the voltage of the boost converter also increases. I think that it'll be more efficient use of the battery, as there is no need for 12 volts for lower volume and as I increase the volume the voltage also increases accordingly.
I can't seem to figure it out how to design such circuit, so I need help.
David Hess:
It is definitely possible to do and similar to how class-H amplifiers work.
For simplicity I would peak detect the input signal and use that as the reference for the regulator which multiplies it to the final supply voltage, with a fast attack and slow decay time.
NiHaoMike:
--- Quote from: David Hess on September 07, 2020, 03:24:53 am ---For simplicity I would peak detect the input signal and use that as the reference for the regulator which multiplies it to the final supply voltage, with a fast attack and slow decay time.
--- End quote ---
You'll need a pretty significant delay in the main signal path for envelope tracking to work well and the savings for such a small amplifier would be largely cancelled out by the power needed to run the logic. Adjusting the supply voltage based on volume setting works nicely. That can be done with another potentiometer on the volume control or program the microcontroller handling the volume control to also set the voltage.
trobbins:
I would think you need to additively combine the XL6009 reference level with an increment that is derived from the signal amplitude (as David Hess indicates). That way if there is no signal then there is no change to the base level regulated output voltage (regulated for both input and output level changes).
However the XL6009 has an internal reference that you can't access, which makes your request a bit trickier to implement. One option is to use a signal based voltage or current supply to pull down the feedback level to the XL6009, and fool it to raise the regulated DC output beyond what it does for line and load regulation control.
David Hess:
--- Quote from: NiHaoMike on September 07, 2020, 03:42:46 am ---
--- Quote from: David Hess on September 07, 2020, 03:24:53 am ---For simplicity I would peak detect the input signal and use that as the reference for the regulator which multiplies it to the final supply voltage, with a fast attack and slow decay time.
--- End quote ---
You'll need a pretty significant delay in the main signal path for envelope tracking to work well and the savings for such a small amplifier would be largely cancelled out by the power needed to run the logic.
--- End quote ---
I would just accept clipping on the first peak, with a relatively long decay time constant.
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