LME49811TB Power supply 200V

[CorySCline]

Hello all!

I am using the LME49811TB to build a large stage amplifier. the issue I'm running into is the power supply problem. I have done a few hours of research to no avail, so I will ask for an answer from knowledgable people . The chip is labeled as a High Fidelity 200 Volt Power Amplifier. However, the **broken link removed**shows "Wide operating voltage range ±20V to ±100V".

2 Questions are present:

1) What are the actual voltage requirements?

2) How do I go about designing a power supply?

In reference to question 2: I have discovered that I need 2 capacitors, a transformer, and a bridge rectifier. How do I pick these out?

 

[Nigel Goodwin]

If you have to ask such basic questions I would seriously suggest you don't try and design your own amplifier, you also need to bear in mind that the chip is only a driver, you need to add a fair amount extra to make an amplifier.

If you want to build an amp, I suggest you look at the 'gain clone' designs.

 

[CorySCline]

I appreciate the concern and understand the risks involved. This is why I am asking for help. I am a careful man and I put a lot of time into doing things correctly and safely. I simply wish to learn. I do not intend to sound rude and I do not take your warnings lightly. however, I intend on proceeding with this project. Any advice on where to learn the required knowledge would be awesome

 

[CorySCline]

As an addition I have successfully completed an LM386N4 amp circuit and this one seems, while more complicated (and dangerous), it seems similar. I did the small one as a test of my dedication and willingness to learn.

 

[CorySCline]

Ok. After much research and the lack of information on how to design my own, I have decided to jsut purchase a pre made one. I have finally decided on the following. Will someone please compare the datasheets to make sure that I actually picked one that will work?

Datasheets:
Power Supply: LPT46
Chip (And associated recommended circuit): **broken link removed**

Thanks!

 

[Nigel Goodwin]

As an addition I have successfully completed an LM386N4 amp circuit and this one seems, while more complicated (and dangerous), it seems similar. I did the small one as a test of my dedication and willingness to learn.

An LM386 is on an entirely different scale, and there's no design involved in it, plus it's pretty indestructible - a high voltage discrete amplifier (even using a driver IC) is vastly more tricky. Apart from potential shock hazards, you're VERY, VERY likely to destroy all the components - any minor mistake and everything tends to go. Looking at the datasheet for the driver chip, I would imagine layout is pretty critical as well.

 

[audioguru]

You selected a +5V, +12V and +24V power supply with a max power rating of only 40W. It does not produce the additional negative voltage required. The IC needs much more voltage. The power rating of the +24V on this weak power supply is only 24W.
The +24V from the 40W power supply will allow a max output from an amplifier (that works with a supply of only 24V) of 14W into 4 ohms and 10W of heat.

 

[alec_t]

The maximum rated supply voltage for the LME49811 is +- 100V. It is wise to allow some margin, say 20%, in the design of an amp supply, so IMHO if you intend using the chip in an amp which maximises its potential you should be looking for a supply which provides around +80V and -80V. At that voltage an 8 Ohm load will draw 10 Amps from external power amp stages driven by the chip. Again allowing some margin, I would suggest the supply should give at least 12A.
It is not a trivial task to build such a supply. You would also need to consider safety. Some sort of voltage regulation and current limiting of the power supply would be necessary/advisable, in addition to any overload protection provided by the amp.

 

[CorySCline]

Thank you Audio and alec I have come to the conclusion that this project should be held off until I build up my knowledge. I have decided I will try an LM3886TF Chip instead, . BTW nigel...thanks for your concern. I dont intend to slap you in the face, I just dont give up easy

 

[Nigel Goodwin]

Thank you Audio and alec I have come to the conclusion that this project should be held off until I build up my knowledge. I have decided I will try an LM3886TF Chip instead, . BTW nigel...thanks for your concern. I dont intend to slap you in the face, I just dont give up easy

I would suggest you first consider what you want the amplifier for, how much power you want, and what impedance speaker you want.

These are all design choices BEFORE you can start designing an amp, and also tell you what PSU you need (and not the little switch-mode ones you posted).

 

[peterlonz]

Surprising to me at least:
No-one has mentioned the relatively small size of the originally selected IC: LME 49811 TB.
15 pins, 10 at about 1 mm centres,....................
This surely would be most difficult to deploy even for an experienced technician skilled at soldering multi-pin small ICs.

 

[pilko]

The pins are staggered and therefore around 2mm spacing.

pilko

 

[audioguru]

Modern ICs like the LME49811 are made for a robot to solder, not a human.