6 channel LME49830 power amp - Page 14

fab · 11th May 2009, 01:33 AM

Quote:

Originally posted by cuibono
Thanks for your input! I've been looking at a lot of other LME chip family designs, and they almost always have resistors between the the gate drive lines (even the LME49830 pdf has them - often the value is around 12k total). Interesting that yours don't. Where did you get them?

The schematics I have from http://www.chp-pcb.cn/ has protection diodes (zener in series with 1N4148) instead of the 12k resistors. This schematics is propriatery of this company so I suppose I can not put it here. This is standard practice to protect mosfet. However, this web site is off-line since a few days...

cuibono · 12th May 2009, 12:28 AM

So I've tried a number of things: I heated and pulled off all the copper on the pcb that was filling unused space. Tested that. Then I cut off the output section and re-did it point to point on the heatsink. Tested that. The results? No difference in the square wave ringing. So I doubt the layout has anything to do with it.

I tried adding 6.8k resistors in the Rbo positions - didn't do anything.

I tried different values of compensation caps (going from 20pF to 22 then 27). Didn't do anything.

What else could I try?

cuibono · 14th May 2009, 04:47 PM

Success!

Square wave is square - I'll post pics later (its too hacked apart right now).

Thank to Segran for the winning tip - the LME supply bypass caps have to be connected to POWER ground, not SIGNAL ground as shown in AN-1850.

Very nice, thanks Segran.

ramiro77 · 6th August 2011, 03:20 PM

Any PCB to build this amplifier?

AndrewT · 6th August 2011, 05:13 PM

Panson was developing PCBs for that series of amps.
Ask.
Comparing LME49810, 49830 and 49811

ramiro77 · 7th August 2011, 01:52 AM

Hey nice thread Andrew!
Thank you so much!
I´ll take a look now and see if there is something that i like.

12th May 2009, 12:28 AM	#132
cuibono diyAudio Member Join Date: May 2006 Location: City of Angles	So I've tried a number of things: I heated and pulled off all the copper on the pcb that was filling unused space. Tested that. Then I cut off the output section and re-did it point to point on the heatsink. Tested that. The results? No difference in the square wave ringing. So I doubt the layout has anything to do with it. I tried adding 6.8k resistors in the Rbo positions - didn't do anything. I tried different values of compensation caps (going from 20pF to 22 then 27). Didn't do anything. What else could I try? __________________ double complete rainbow all the way!!

14th May 2009, 04:47 PM	#133
cuibono diyAudio Member Join Date: May 2006 Location: City of Angles	Success! Square wave is square - I'll post pics later (its too hacked apart right now). Thank to Segran for the winning tip - the LME supply bypass caps have to be connected to POWER ground, not SIGNAL ground as shown in AN-1850. Very nice, thanks Segran. __________________ double complete rainbow all the way!!

6th August 2011, 05:13 PM	#135
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Panson was developing PCBs for that series of amps. Ask. Comparing LME49810, 49830 and 49811 __________________ regards Andrew T.

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6th August 2011, 03:20 PM	#134
ramiro77 diyAudio Member Join Date: Jun 2010	Any PCB to build this amplifier?

7th August 2011, 01:52 AM	#136
ramiro77 diyAudio Member Join Date: Jun 2010	Hey nice thread Andrew! Thank you so much! I´ll take a look now and see if there is something that i like.

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