Possible to bridge both TDA7053A channels into one load?

[HankMcSpank]

I've been dabbling trying get sufficient power out of a mono TDA7052A 1W audio amp IC into a 6 ohm load - basically the thing works for about 5 seconds then the waveform turns ugly as the IC heats up. Now one possibility is to heatsink it, but the package is quite small (DIP08) & I'm limited for space anyway.

I need a mono IC of about 1.5W (into 6 ohms @9V) preferably in a DIP packaging (there aren't that many about!)

So I've turned my attention to a stereo IC of the same family - a TDA7053A. Now this is DIP16 and therefore more 'IC surface area' to put a heatsink onto to help disappate the heat. It's not possible to use the thing with just one channel as there's inbuilt shutdown should the 'current disparity' between the two channels become too great - so I was wondering if I could simply feed the one mono signal into both channels & then in turn take the outputs from each amp channel and combine them across the load?

Therefore, feeding the same signal into both channels, and wiring as follows...

TDA7053A CH1 & CH2 +ve output -> speaker +ve connection

TDA7053A CH1 & CH2 -ve ouput -> speaker -ve connection

Now I'm figuring that in principle it should work (I don't have the TDA70523A yet, else I'd just trry it because erhmm.....there as cheap as chips )

Any thoughts?

[AndrewT]

Hi,
is your 6ohm load a headphone?
1.5W into 6r0 is equivalent to ~4.2Vpk and 700mApk into that resistive load.

I don't think you will find many/any dip packages that can deliver that current.
If the load is reactive then expect the transient current to approach 2Apk.

[HankMcSpank]

The single amplifier (mono) load is not headphones...but is in fact a 6 ohm coil.

I'm more interested in whether this is do-able from a bridging perspective vs the numbers behind the issue, but since you've taken the trouble to calculate them, I should clarify - the 1.2W I seek is not a constant 1.2W (but peaking now & then & only for transients) ...the normal power level will be significantly lower.

When I mentioned the 6 ohms...I should have been clearer - that's a DC coil resistance figure.

The actual overall impedance works out at approximately between 7 Ohms thru 9.5 Ohms for the frequency band involved.

At a normal operating condition of about 3V pk, if my calculations are correct
...
2.13V RMS driving 7 Ohms = 304mA/608mW

or when it's maxing out at 4V pk (transients), I calculate....

2.83V RMS driving 7 Ohms = 404mA / 1.1W)

Hence wanting a package that'll deliver 1.2W.

But parking that for a moment - I seek a general opinion on the 'bridging' ethos here ....is it considered bad form, not practical blah blah?

[pacificblue]

The TDA7053 consists of two bridged amplifiers. You won't gain anything by bridging it again.

You could try the TDA2822. It comes in a DIP16 case and can be bridged. There is a similar TDA2822M in DIP8 package, but in view of your heatsinking issue, the TDA2822 is probably the better choice.

[AndrewT]

my opinion is forget bridging.
With your 8ohm load each half of the bridge amp is driving half power into 4ohms, i.e. ~2Vpk & 0.5Apk into 4r0, or about half a watt.
The bridged pair will try to deliver 1W into 8r0, but the transient current into a reactive 8ohm speaker load can approach 1.5Apk and this has to flow through both the amps creating the bridged amp.

[HankMcSpank]

Originally Posted by pacificblue

The TDA7053 consists of two bridged amplifiers. You won't gain anything by bridging it again.

You could try the TDA2822. It comes in a DIP16 case and can be bridged. There is a similar TDA2822M in DIP8 package, but in view of your heatsinking issue, the TDA2822 is probably the better choice.

I'm not trying to gain power....but more spread the heat loading (ie rather than 1.2W cooking a small mono DIP08, I figured a DIP016 would lighten the load ...feed the mono signal into both channels thereby spreading the current/heat load across the larger real estate)

Re the TDA2822 - I need the IC to have an mute/inibit pin - the TDA7052A & TDA7053A are essentially muted when 0V is placed on the DC VOL cntrl pin....it looks like the TDA2822 has no such pin available.

[pacificblue]

Originally Posted by HankMcSpank

the TDA7052A & TDA7053A are essentially muted when 0V is placed on the DC VOL cntrl pin....it looks like the TDA2822 has no such pin available.

That is right. You would have to interrupt the supply voltage to mute the TDA2822.

[richie00boy]

You would need low ohm matching resistors on the spk+ and spk- lines of each half of the chip, 4 in total.

[bourlotg]

I think that you need the TDA7056

[Th3 uN1Qu3]

What's your application more specifically? The TDA2822 should do it, but it's quite noisy in bridged mode.