LM4766 Questions: Rl and Single Power Supply

[69stingray]

Hello Everyone, great forum. I am getting interested in building my own chip amp.

Can the LM4766 drive a 4-ohm load? All the documentation states 8-ohms - but I can not find a tolerance or minimum.

Has anyone done a LM4766 design with a single power supply? I think building a 40W x 4 amp for an DSP speaker project and it would be nice to have one 18V x 18V transformer driving two 40Wx2 LM4766 (or similar) chips.

Thanks for the input.

Link to datasheet: http://www.ti.com/lit/ds/symlink/lm4766.pdf

 

[abraxalito]

I built an active XO and amp setup using LM4766s in BTL on a single supply. I'd definitely not recommend this chip for 4ohm duty, the output current is only guaranteed to 3A. I used output transformers in my implementation.

 

[69stingray]

Thanks abraxalito

 

[PRR]

...Can the LM4766 drive a 4-ohm load? All the documentation states 8-ohms...
Has anyone done a LM4766 design with a single power supply?
Link to datasheet: http://www.ti.com/lit/ds/symlink/lm4766.pdf

Did you read the sheet you linked?

Page 6 shows single-supply connection.

Page 6 also shows a Bridged connection apparently driving 8 Ohms, which is a 4 Ohm load on each amplifier channel.

However figures 17 and 18 on page 10 shows what you ask: output for various loads. At +/-30V the power peaks at 6 Ohms and is way-way down at 4 Ohms, due to both overheating and the 3-4A limit that abraxalito refers to.

 

[asuslover]

Take a look here :
Xkitz.com
Lm4766 is one of the power chips they are using in their amps. And single power supply.

 

[69stingray]

Thank you PPR. First of all, how is Maine these days? I just spent a week in Eustis while skiing at Sugarloaf - but I degrees.

Did you read the sheet you linked?

Page 6 shows single-supply connection.

Yup, saw that and that is what gave me the idea to ask if anyone has attempted this before.

Page 6 also shows a Bridged connection apparently driving 8 Ohms, which is a 4 Ohm load on each amplifier channel.

Thank you PRR. I was not sure If I could make that leap that a bridged channel driving 8-ohm could have two channels driving 4-ohms.

However figures 17 and 18 on page 10 shows what you ask: output for various loads. At +/-30V the power peaks at 6 Ohms and is way-way down at 4 Ohms, due to both overheating and the 3-4A limit that abraxalito refers to.

I did miss this graph. You are correct, it drops like a rock below 6-ohms.