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Class D Switching Power Amplifiers and Power D/A conversion

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Old 4th September 2012, 12:14 PM   #11
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Here it is, but i suggest to read the datasheet as well to understand why/what/ is why/what.

The Outputs needs to be bridged in parallel. (L+/R+ & L-/R-)

Regards,

doc
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Last edited by doctormord; 4th September 2012 at 12:18 PM.
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Old 4th September 2012, 02:56 PM   #12
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TY doctormord you are a genius.
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Old 27th January 2013, 09:58 AM   #13
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I'm novice so sorry for stupid question
How to implement "HIGH" of SHDN and MUTE in this schematic? or how can i drive it to LOW
and why MUTE(pin31) have a 10k instead of link with SHDN, which is shown in datasheet?
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Old 19th February 2013, 10:19 PM   #14
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Hi,

haven't got a notification for your reply, so sorry for the delayed answer.

As you can see, /SHDN and /MUTE are low-active, so, to enable the chip (/SHDN) and unmute it (/MUTE) both needs to be on high-level. Thats why /SHDN is connected to the 10k/10k Divider R6/R7 forming a high-level from VDD.

/MUTE is connected in that way, that the chip gets muted whenever the thermal-protection trips. R1 & C5 is forming a time-constant to filter this signal and mute ringing from the set thermal-trip-point. As from the datasheet you'll see, that /TEMP is open drain and needs to be connected to either REG (internal 6V regulator output) or high-level. So why did i connected this to HIGH rather than REG is, that the REG-output is not active in /SHDN mode and you may get in trouble while power-up-sequence. I had problems with this behavior when using the MAX9704 chip.

In normal operation, /TEMP is internally on high-level and the pin is "open drain output". So /MUTE is somewhat "high" as well. When thermal-protection is kicking in, this pin goes low and mutes the device. When the temp gets down, the chip is unmuted again.

Have a look into the dev-kit datasheet here:

MAX9709EVKIT Evaluation Kit for the MAX9709 - Overview


I made some PCBs now running here. 2x50W Mono.
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Last edited by doctormord; 19th February 2013 at 10:21 PM.
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Old 21st February 2013, 06:43 PM   #15
sst4270 is offline sst4270  United States
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Default max9079 Amp

Hello Doctormord,

Are you planning to sell those boards? Already stuffed?
I'd be interested in purchasing a pair of those boards with components installed.

Please PM me.

Regards,

Steve
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Old 23rd February 2013, 06:13 PM   #16
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by necrofago View Post
TY doctormord you are a genius.
+1 to that! Very impressive amp the size of a matchbox. Why people still want to play around with a 70 lb class A home heater amp I don't know. The future is here.
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Old 23rd February 2013, 10:06 PM   #17
redjr is offline redjr  United States
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Originally Posted by xrk971 View Post
....Why people still want to play around with a 70 lb class A home heater amp I don't know. The future is here.
I agree. I guess there are a lot of purists that do! There are a lot of very nice sounding class D amps to build, or buy commercially.
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Old 23rd February 2013, 11:18 PM   #18
xrk971 is offline xrk971  United States
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The transition and rise of Class-D is similar to what happened with analog vinyl records to CD's. Essentially, the CD player has a small low power DAC that makes line-level signals from digital music data. The Class-D amp is essentially taking that line-level DAC (typically drives a 10 kOhm load up to a few volts) and made it speaker-level DAC, or as a ADC-to-DAC since we are still feeding it RCA line-level inputs. Some Class-D's have optical or USB digital input and you would think they can skip the ADC but in reality, I think there is still an internal line level ADC to line levels which are then fed to amp. If people are happy with the signal that their CD player produces at line-level, there is no reason why they should not be happy with the same concept applied to a 8 ohm load driven to say 24 volts. I suppose there are still people who insist in the "lossless" analog signal from a vinyl record or reel-to-reel... Then there are folks who still insist on tubes... that is another story. Although I hear the new TPA31xx's from TI are as good or better than some tube amps.
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Old 28th February 2013, 08:33 AM   #19
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Why should there be an internal ADC?. Some amps do and some amps don't. The Sinewave amps do have ADC internally, but many T.I. based amps like Lyngdorf (developed by Lyngdorf and sold to T.I.), Sumoh and panasonic don't.

I have a MiniAMP from MiniDSP that creates the PWM signal fed to the poweramp from an I2S input or spdif.
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Old 19th October 2013, 10:45 AM   #20
juanito is offline juanito  Europe
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Seen this?
HTM AUDIO 50 WATTS CLASS D AMPLIFIER MODULE
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