LME49810 - a new cousin for LM4702 - Page 11

AndrewT · 16th August 2007, 10:39 AM

Quote:

Originally posted by panson_hk
For current-limited regulator, you proposed a shunt regulator? The chip's Iq is 11/13 mA. If the CCS is set at 50 mA, a shunt transistor will consume about 39 mA x 60 V = 2.34 W in idle mode. Will it be too much?

Hi,
using a transistor with 10W 100MHz to 200MHz hFE100 to 150 would dissipate your 2.34W using a 10C/W sink at ambients upto 30degC. and Tj still below 90degC.
I have not yet implimented either series or shunt front end regulation so have no opinion which sounds better.
The inherent current limit of CCS + shunt is attractive.
The few papers I've read seem to suggest that noise suppression is better with a good shunt.

panson_hk · 16th August 2007, 04:05 PM

Quote:

Originally posted by AndrewT

The few papers I've read seem to suggest that noise suppression is better with a good shunt.

Hi Andrew,

Yes, I have seen many articles, reports, projects saying shunt is better then series - for Hi-end!

Panson

monkey29 · 29th August 2007, 07:24 AM

LME49810 Audio AMP (Samples)

monkey29 · 29th August 2007, 07:33 AM

LME49810 Audio AMP (Samples) No2

monkey29 · 29th August 2007, 07:36 AM

LME49810 Audio AMP (Samples) No3

CJ900RR · 29th August 2007, 11:58 AM

Interesting circuit! And I like your design monkey. Nice indeed. What kind of output transistors do you think would be best to use?

Im new on class-a and have some questions on the output stage. How do you increase power. Is it correct as I did in the attached file? (Take no notice on the transistors I only picked a random one.)

Also, how do you callculate output power? I guess it has to do with the MOSFETs or?

Best regards...

panson_hk · 29th August 2007, 02:46 PM

Quote:

Originally posted by CJ900RR
How do you increase power.

Best regards...

You may try Leach SuperAmp output topology

http://users.ece.gatech.edu/~mleach/superamp/

megajocke · 29th August 2007, 03:02 PM

Your distortion plot seems to indicate that it actually already IS current limited.

If we assume it is current limited at 50mA it would be able to provide about 35mA RMS to the load before clipping and high distortion. The 100 ohm load curve shows distortion coming in slightly below 4 volts. 35mA*100R = 3.5V. The 600R load shows clipping setting in at around 20V. 35mA*600R = 21V.

panson_hk · 29th August 2007, 03:10 PM

Quote:

Originally posted by megajocke
Your distortion plot seems to indicate that it actually already IS current limited.

Yeah! I would say so based on the data.

veteran · 1st September 2007, 10:30 AM

I can't wait to start assembling this amplifier so I designed my version of PCB and ordered some boards:

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29th August 2007, 03:02 PM	#108
megajocke diyAudio Member Join Date: Jan 2003 Location: Solna	Your distortion plot seems to indicate that it actually already IS current limited. If we assume it is current limited at 50mA it would be able to provide about 35mA RMS to the load before clipping and high distortion. The 100 ohm load curve shows distortion coming in slightly below 4 volts. 35mA100R = 3.5V. The 600R load shows clipping setting in at around 20V. 35mA600R = 21V.

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