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Old 25th October 2005, 12:08 AM   #11
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Very exciting, I can't wait to get my sample's. I've moved away from chip amps but these seem worth the time.
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Old 25th October 2005, 12:29 AM   #12
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Has anyone done any "back of an envelope" math on current consumption and voltage requirements on one of these?
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Old 25th October 2005, 02:53 AM   #13
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Default LM4702

This is the same package as the 3875,76,86 ect..... is a power darlington complimentary output pair with much higher power handling up to +- 70V to as high as 100 +- dissipation is still only 125W quiescent current is 30 ma distortion is .004 at 14RMS out, it actually is not as good overall as its conterparts just handles higher power supply voltages................
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Old 25th October 2005, 07:12 AM   #14
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Default Re: LM4702

Quote:
Originally posted by MikeLewis
From the Spec Sheet:

POWER DISSIPATION AND HEAT SINKING
When in “play” mode, the LM4702 draws a constant amount
of current, regardless of the input signal amplitude. Consequently,
the power dissipation is constant for a given supply
voltage and can be computed with the equation PDMAX = Icc
* (Vcc – Vee). For a quick calculation of PDMAX, approximate
the current to be 25mA and multiply it by the total supply
voltage (the current varies slightly from this value over the
operating range).


Constant power draw? This sounds like it's going to be a real hog. Is this Class A?

Quote:
Originally posted by tiltedhalo
This is the same package as the 3875,76,86 ect..... is a power darlington complimentary output pair with much higher power handling up to +- 70V to as high as 100 +- dissipation is still only 125W quiescent current is 30 ma distortion is .004 at 14RMS out, it actually is not as good overall as its conterparts just handles higher power supply voltages................
Guys do the maths...

Sure it's Class A, but it's a DRIVER not a power amplifier. To build a complete amplifier you need to add external components for the output stage and that's where the big power disspation will be. The current for the driver IC is 25 mA and the current available model in production is the A grade which means maximum +/- 75 VDC supply. This gives Pmax=(75-(-75))*0.025 W = 3.75 W of dissipation. Yes, that's less than 4 W. No need to worry...
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Old 25th October 2005, 03:38 PM   #15
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Nice thing !

The point is to find the suitable power follower for this awesome chip, and have the money for the heatsink invloved

Gainclones may still remain the most popular chip amps
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Old 25th October 2005, 10:34 PM   #16
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Hi

Cool stuff in deed for the power hunger guys...

Who can recommend the power output transistors to be used with this chip LM4702...

Thanks
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Old 27th October 2005, 07:44 PM   #17
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Quote:
Originally posted by metal

Who can recommend the power output transistors to be used with this chip LM4702...

Thanks

MJ11032 from Onsemit should work fine, samples are available. I know I've had a sample request on the 4702 for over a month... it's on backorder... anyone actually play with them yet?



Quote:
Originally posted by pinkmouse
That does look very interesting.

However, this looks much more fun!
I agree! I actually got that chip, but it is surface mount and incredible small! I can't handle soldering it... anyone else upto the challenge?? I'd be willing to work out some sort of trade/purchase if you could just glue the thing to a piece of cardboard and solder some leads on it!
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Old 27th October 2005, 08:23 PM   #18
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ElementX -- can you make a PCB good enough for it?

You can use solder paste and a toaster oven to actually solder it on. If that's the only component on the board, I expect you would get it right after only a few tries.

http://www.seattlerobotics.org/encod...6/oven_art.htm

Wes
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Old 27th October 2005, 08:40 PM   #19
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***** ********* ******, this is awsome..

I have got to get myself some o'these..
how's nationals sample program these days? just as tight as before i presume?
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Old 27th October 2005, 09:15 PM   #20
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Default Funlight

For ElementX: I have successfully soldered the LM4970 device and
tried it out with a picmicro,it's an interesting device if you are interested in adding some "Bling" to your next project...


BTW: I have a stereo microscope that I used while soldering....Those little buggers look like 18 wheelers under the scope!!


Regards Bob C.
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