PSU Design for car audio amplifiers using UC2577-ADJ

[faizanbrohi]

Hello Everyone , this is faizanbrohi again to discuss yet another project design . actually it is related to building a Power supply for car audio using a IC UC2577-ADJ and fits the need Perfectly for a 12V battery step up psu.

Main Page : http://focus.ti.com/docs/prod/folders/print/uc2577-adj.html
Datasheet : http://www-s.ti.com/sc/ds/uc2577-adj.pdf
Application Note : http://www-s.ti.com/sc/psheets/slua181/slua181.pdf

The application note discusses a supply for a automotive application but has less voltage specification and less current specification . The absoulute maximum rating is good for my design as i require +55V and -55V @3A or @6A so since this is a single mode supply , We can make two identical units and then joing them serialy like two voltage sources producing +55 and -55V . Sounds Really Good , But SOme Calculation is needed . The Datasheet is very comprehensive in providing the adequate information for each and every thing. THere is only theoratical Calculations THat need to be done .

The Pictures For the Block Diagram are included and the Absoulte Ratings along the Note .

View attachment 39684

View attachment 39685

 

[ante1]

I would call this unnecessary littering!

 

[audioguru2]

Hi Faizan,
This is a positive stepup converter. It has the same ground as another one. So it cannot be used serially to get a negative voltage unless the two circuits are completely separate.

In two different cars?? One car would have a positive supply and the other car would have a negative supply. Hee, hee. ;D

That is why high power car amplifiers have a stepup inverter that uses a transformer so its output can be rectified to give positive and negative voltages.

 

[faizanbrohi]

I think you are right but the problem is that is there any converter capable of Positve to negative voltage conversion having high amperage . or any other distinct method to convert positive to negative

 

[audioguru2]

I think you are right but the problem is that is there any converter capable of Positve to negative voltage conversion having high amperage . or any other distinct method to convert positive to negative

You don't want a converter. You want the power supply circuit to be a high frequency inverter with a transformer, not just a coil. Then a full-wave rectifier at its output provides positive and negative high voltages.

 

[faizanbrohi]

Well THere can be another way why not invert the voltages using TI OPA548 configured as an inverting amplifier with gain 1 , ie configured as a voltage regulator
it is capable of 60V @ 3A (3000mA) , since it has inverting negative ouptut it will work .

 

[audioguru2]

I said that you should use a DC to AC inverter, not an inverting amplifier. An inverting amplifier with a negative output needs a negative supply that you don't have!

 

[faizanbrohi]

actually it is you can operate it on a single supply see this application note of OPA548 http://www-s.ti.com/sc/psheets/sboa059/sboa059.pdf

 

[audioguru2]

actually it is you can operate it on a single supply

You can properly bias and capacitor-couple the load on any opamp or power amplifier.
For a high power amplifier, the single supply voltage must be very high.

 

[faizanbrohi]

so you are saying we can invert it but the voltage will be less , i mean if we give the OPA548 60v and give it input 60v also and use inverting configration will it not produce -60 at the output

 

[audioguru2]

The OPA548 is a power opamp. If it has a +60V and 0V supply then its output will be from +2V to +58V, it won't be negative. Even if it is connected as an inverting opamp with a gain of one, then with a +2V input its output will be +58V and with a +58V input its output will be +2V.

An opamp doesn't make a supply voltage. It uses a supply voltage that is frequently positive and negative.

To make a high voltage positive and negative supply for your car's high power amplifier, you need a DC to AC inverter circuit (a high power oscillator) with a stepup transformer in it, then it feeds a rectifier to make a positive high voltage and a negative high voltage.