# Converting split supply amplifier to single supply

1. Jan 14, 2014

### Tesladude

I am talking about those 5pin AB amplifiers like the tda2030 for example.
You can power them with posotive and negative 12v, which is equal to a total 24v,

Or you can modify the circuit for a single supply, but if you do that so you can use a single supply12v, is it equivalent in output power to the posotive and negative 12?

2. Jan 15, 2014

### sophiecentaur

If you look at the Datasheet (they are available for all integrated circuits and usually free) then it will tell you the conditions it can operate on. Without looking at the sheet, though, you can predict that the maximum peak to peak voltage swing will only be half of the nominal 24V with a double power supply. If you want to deliver the same power with half the voltage swing, the amplifier would need to supply twice the current (into a appropriate load resistance, of course). But that doesn't tell the whole story; the maximum rating would be device specific.
Any more, depends upon your level of expertise.

3. Jan 15, 2014

### Tesladude

I split supply amp simply switches between useing negative and posotive voltage as the output, so can the single supply not put out 12v or does it split and pit out 6v

4. Jan 15, 2014

### sophiecentaur

You need to draw a diagram for a proper discussion. Or you can look at the spec sheet with its diagrams.

5. Jan 15, 2014

### Tesladude

Well this applies to any and all class AB amplifiers though, and I am not asking help with components or circuits which makes a diagram irrelevant.
I have checked the datasgeet of all class AB amplifiers I know many a times and have never seen an output vs single supply voltage graph although the ic is able to be used with a single supply. So does the graph showing output power vs say; +-12v
Also apply to the chip with a single supply of 12volts.

In a split supply amplifier with positive and negative 12v the speaker will only evey see 12v, but with a single supply is it able to put out all the 12v or only positive and negative 6.

6. Jan 16, 2014

### Staff: Mentor

Your posts in this thread are not making much sense to me so far.

When you want to convert a split supply circuit to a single supply circuit, there are two issues. The first is reduced voltage headroom. You have less voltage to swing your inputs and outputs between, and even less than that for most amplifiers (check the datasheet for input CM voltage range, and output voltage swing).

The second issue has to do with offsetting the input voltage waveform from ground-referenced to half-supply-referenced. This involves an RC time constant that can be problematical for good waveform fidelity.

Why not just do an inverter DC-DC circuit followed by a linear negative regulator to give you a nice negative supply?

7. Jan 16, 2014

### meBigGuy

To me this is a non-question. Like asking what happens if I light a bulb with 3V battery in place of two 3 volt batteries? The math is simple. The offset problems are obvious. The datsheet says what you can do. Not sure how to help. If you try to draw an example for your question and show the output waveform, you will see that you already know how to determine the answer.

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