LJM LME49810 IC AMP

ljm_ljm

Member
2006-09-26 6:47 am
Although this speech is 2016, but this design was a decade ago.
The design of 2006.
About the chip issue not too long, I designed the.
The LME 49810 is the United States, the national semiconductor's latest flagship amplifier chip.

Due to the common IC power amplifier is a single integrated circuit chip.

In other words, audio amplifier input stage amplifier stage, output stage, are all on the same chip.

Power output stage will produce larger quantity of heat, and the heat will feedback to the same chip small signal input stage, and the signal amplifier stage at the corresponding level.

The mechanism of distortion is called thermal distortion. This in SELF book also have detailed records, and testing.

So NS national semiconductor in order to solve this problem, in later products launched in 49810, the LME LM49830 series power amplifier IC.

49810 is the small signal amplifier stage, the design of the separation of the current output stage,

This has greatly increased the power amplifier

I could have a relatively long time to analyze it, test.

I have put them idle time for ten years, so, don't worry so much days.


Behind I would have taken the free time to complete test and analysis it.
 

Attachments

  • IMG_5231.JPG
    IMG_5231.JPG
    133.7 KB · Views: 1,041
  • Like
Reactions: 1 user

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
Sorry to be the bearer of bad news, but Texas Instruments (who acquired National Semiconductor in 2012) discontinued the LME49810, LME49811, and LME49830. The lifetime buy ends in September, but the chips are already very hard to find. Among the various distributors world-wide, there's only a small handful (<10) of the ICs in stock.

Tom
 

ljm_ljm

Member
2006-09-26 6:47 am
Sorry to be the bearer of bad news, but Texas Instruments (who acquired National Semiconductor in 2012) discontinued the LME49810, LME49811, and LME49830. The lifetime buy ends in September, but the chips are already very hard to find. Among the various distributors world-wide, there's only a small handful (<10) of the ICs in stock.

Tom

I know that acquired Texas instruments.
But the chip can be easy to buy.
This does not affect our use, LME49810 I think is still the most excellent high performance products in NS, flagship model.

If you are interested in purchasing, I can help about less than $4-5.

Of course, there are still LME49811, I think that is the same with the LME 49810 basic products.
 

Attachments

  • 49810.jpg
    49810.jpg
    128.3 KB · Views: 943

billshurv

Member
Paid Member
2014-03-01 11:53 pm

ljm_ljm

Member
2006-09-26 6:47 am
Using an LME49811 in a circuit designed for an LME49810 will also require a bit of redesign as the '810 has an additional emitter follower on the output that the '811 does not have. The two are not plug-n-play compatible.

Tom

B: yes. They are not the same of the PCB.

But the principle is similar.

The same place is that they have a very good performance.

Although they are not necessarily the most beautiful.

But I still think they are certainly better than any LM3886.

Their output power tube is not on the same chip with the small signal input circuit,

The chip will not produce thermal distortion of feedback. Can basically with excellent discrete component power amplifier.
 
You need a much bigger heatsink for LME498xx to operate in minimal distortion condition.
Yes,which is why I haven't bought your compact series board yet. Compact Series
50 W. what were you thinking? LM3886 will to 60 W.
I can't make boards without an enviromental mess like the whole coast of your country. I need 200 W peak. So I'm thinking of buying your boards and installing remotely output devices 3 pair TIP142/146 on 13 cm x 17 cm x 4 cm heatsinks I own already. VFD motor drive salvage enclosures. BD139 stacked on TIP142 as heat sense diode. Wires from board to OT will have to fly like a Leak 70 or dynaco ST120, if there is oscillation I'll try series 8 turn coils out of blown PCAT switcher supplies.
Mircea board has the output transistors on the edge, but he won't sell to the USA.
I have 30 LM49810 bought the week of the discontinue announcement. Digikey will still sell you 640 of them for $7 apiece.
 

ljm_ljm

Member
2006-09-26 6:47 am
Yes,which is why I haven't bought your compact series board yet. Compact Series
50 W. what were you thinking? LM3886 will to 60 W.
I can't make boards without an enviromental mess like the whole coast of your country. I need 200 W peak. So I'm thinking of buying your boards and installing remotely output devices 3 pair TIP142/146 on 13 cm x 17 cm x 4 cm heatsinks I own already. VFD motor drive salvage enclosures. BD139 stacked on TIP142 as heat sense diode. Wires from board to OT will have to fly like a Leak 70 or dynaco ST120, if there is oscillation I'll try series 8 turn coils out of blown PCAT switcher supplies.
Mircea board has the output transistors on the edge, but he won't sell to the USA.
I have 30 LM49810 bought the week of the discontinue announcement. Digikey will still sell you 640 of them for $7 apiece.

TIP142 147 Using the voltage does not exceed + - 50 v.

Because of its VCE withstand voltage is 100 v.

It may not work in the voltage is greater than + - 50 v, though this can also be used, but in actual output more than + - 50 v voltage, voltage on both ends of the VCE at more than 100 v.

This will damage.

And TIP142 TIP147 frequency is low, in the actual use of time, the distortion will be very expensive.

It is recommended to use MJE15030 + TTA1943 TTC5200

Or 2 sa1930 +TTA 1943
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
B: yes. They are not the same of the PCB.

But the principle is similar.

The same place is that they have a very good performance.

Although they are not necessarily the most beautiful.

But I still think they are certainly better than any LM3886.

Well, that depends. If your PCB layout is good, you can beat the performance of the stock LM3886 with the LME49810. However, if you screw up your PCB layout, and it doesn't take much to do, you will not be able to beat the data sheet performance of the LM3886, at least not on THD+N. In particular the output nodes (drivers, Vbe multiplier, compensation pin) are sensitive nodes on the LME498xx ICs.

Do you have any measurements of how your circuit performs? THD+N vs output power and THD+N vs frequency, for example?

Tom
 

ljm_ljm

Member
2006-09-26 6:47 am
Well, that depends. If your PCB layout is good, you can beat the performance of the stock LM3886 with the LME49810. However, if you screw up your PCB layout, and it doesn't take much to do, you will not be able to beat the data sheet performance of the LM3886, at least not on THD+N. In particular the output nodes (drivers, Vbe multiplier, compensation pin) are sensitive nodes on the LME498xx ICs.

Do you have any measurements of how your circuit performs? THD+N vs output power and THD+N vs frequency, for example?

Tom

LME49810 + A1930 C5171 + A1943 C5200
Power can easily do 150 w eight ohms.

I don't need to beat LM3886. Because they are not comparable.

And I would like to add, even more low THD, also is not to say that beat this.

An amplifier THD is less than 0.02%, THD is no longer important.

A powerful, low impedance amplifier at the time of use. Damping coefficient difference effect is very obvious

I'll use the oscilloscope measurement. It can be seen that the amplifier is normal and stable.

Then I would have taken the time to use APSYSTEM 2 all parameters measured.

I'm not interested in doing the smallest THD.

I only responsible for all kinds of information on it.
 

Attachments

  • TB2b__uoVXXXXbNXpXXXXXXXXXX_!!36508936.jpg
    TB2b__uoVXXXXbNXpXXXXXXXXXX_!!36508936.jpg
    56.4 KB · Views: 453
  • TB2f.nBoVXXXXa4XpXXXXXXXXXX_!!36508936.jpg
    TB2f.nBoVXXXXa4XpXXXXXXXXXX_!!36508936.jpg
    52.7 KB · Views: 454
  • TB2Z3_roVXXXXcDXpXXXXXXXXXX_!!36508936.jpg
    TB2Z3_roVXXXXcDXpXXXXXXXXXX_!!36508936.jpg
    52.8 KB · Views: 501
  • TB2MHrCoVXXXXamXpXXXXXXXXXX_!!36508936.jpg
    TB2MHrCoVXXXXamXpXXXXXXXXXX_!!36508936.jpg
    369.1 KB · Views: 514
  • TB2hCDRoVXXXXbuXXXXXXXXXXXX_!!36508936.jpg
    TB2hCDRoVXXXXbuXXXXXXXXXXXX_!!36508936.jpg
    305.8 KB · Views: 528

ljm_ljm

Member
2006-09-26 6:47 am
In the actual test, THD are slightly larger than the PDF.

I think that is normal.

By electrolytic capacitor, the effects of input capacitance. MKP might be better.

The influence of the power supply.

In actual production, very fine material, even the conductor can produce distortion of 0.0005%

I also tried different relay, distortion can be increased 0.0002%.

I don't believe anyone do THD is less than the PDF. Including LM3886