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Class D Switching Power Amplifiers and Power D/A conversion

Portable battery powered Class D
Portable battery powered Class D
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Old 6th October 2004, 09:50 PM   #1
edpgc is offline edpgc  United Kingdom
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Location: Birmingham, UK
Default Portable battery powered Class D

Right I'm trying to get as much power out of as few volts as efficently as possible. It seems to get around 4 Watts i need 7 volts. However I was thinking since these class D's are essentially switch mode pwer supplies, why can't they bet set-up to switch a higher voltage than the input voltage? Therefore letting me get 10 Watts or more from 5 volts!?

Has anyone achieved this? Perhaps I should just put a switch mode supply before the class D though I'm sure this is asking for trouble! Any ideas or suggestions for ultra efficient low voltage class D chips!?

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Old 7th October 2004, 09:24 AM   #2
classd4sure is offline classd4sure  Canada
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You mean an audio class d amp working as a buck/boost? Don't think so. Wwhy not add an extra cell to your battery pack?
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Old 7th October 2004, 10:19 AM   #3
Jaka Racman is offline Jaka Racman  Slovenia
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Location: Slovenia

take a look at http://www.jam-tech.com/. You might also search their patents. I do not know if their products work, because you can patent anything .

Best regards,

Jaka Racman
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Old 2nd December 2008, 02:24 PM   #4
Davey T is offline Davey T  United Kingdom
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Join Date: Jul 2007
I was about to post a similar thread but found this one and thought i would expand on it.


The best portable battery loudspeaker/amplifier solutions use a single lipo 3.7v battery which can be charged off usb and doesn't require cell balancing etc. You quiescent power consumption is nice and low too as you are operating from a low voltage = lower switching losses.

However, this limits you to about 2 watts of power.

Most everyday use of the speaker means thats its running within this 2w power usage band. However, some days you would like the ability to really crank it and have 10-20w at your disposal. This would be very useful and a big selling point. BUT How could this be acheived?

a) step-up before the class-d?
b) more battery cells and live with the increased quiescent power consumption?
c) boost-buck?
d) cuk converter?
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Old 6th December 2008, 10:04 PM   #5
ChocoHolic is offline ChocoHolic  Germany
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Steping up with a simple boost converter should do the job.
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Old 8th December 2008, 02:31 AM   #6
ArjenShenzhen is offline ArjenShenzhen  China
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Default steppin it up

Hey there,

You can indeed use a step up converter, but you need to understand that you either use a high voltage, or a high current. if you use 1 A at 12 volts, you have 12 watts, if you want 12 watts at 3.7 volts you need about 3 A, so your battery would be empty much sooner. its a much better idea to use 3X 3.7 volts cells that you can switch parralel for charging, and serial for discharging. and it still keeps it relatively simple.
Then you can use a wide range of medium power IC's.

Class D is best for battery powered systems as they have the highest efficiency.

there are many people selling these boards, and i also have them.

if you need over 20 watts, battery power will claim a more heavy burden on your back as the battery packs are getting heavy, making a more efficient speaker system is also worth allot.
Always check the power supply... and my spelling...
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Old 9th December 2008, 02:03 PM   #7
Davey T is offline Davey T  United Kingdom
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I think i'l stick to the 3-cell in series. I've come up with a neat and simple charging/balancing circuit.

I did think about switching between series/parallel but its a bit tricky to wire up and what if the cells aren't exactly balanced before you put them in parallel?
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