LM3886 power consumption in idle/mute mode

[peranders]

Can you show us the exact schematics? Do you have any oscilloscope for investigating possible oscillations?

 

[zanden30]

It is just this scheme from TI: AN-1192 Overture™ Series High Power Solutions with some modifications. Fig. 3.
CIN = 0,47 uF.
Ci1 = 10 uF elektrolyt
Rb = 47 kOhm.
The test is identical to the scheme. Nu snubber or serial to the speaker.
I will try to measure the output signal with 1N4148 diodes if it gives high frequency signal. My multimeter does not measure any AC signal…..
There is no distortion. It sounds realy very wel..

 

[peranders]

What happens if you disconnect the speaker? Does the current go down? Do you have equal current in both supply voltages?

 

[tomchr]

There are no common resistors (of ca. 0,1 Ohm, what you mean probably).
It is just 2 x a single BTL. So 4 LM3886's (stereo BTL).

You do need those ballast resistors. Basically you're forcing the difference in DC offset between the two LM3886es in parallel across the ballast resistors. Higher resistance value -> lower wasted current but also lower max output power.

I'd insert 0.1-0.22 Ω in series with each output. I bet you'll find that'll reduce the standing current considerably.

Tom

 

[JMFahey]

No parallel LM3886 in the schematic posted.

 

[tomchr]

Ah. I misunderstood Post 20.

Tom

 

[zanden30]

It's only 6,5 mV / 8 Ohm < 1 mA through the speakers.
No speakers connected makes no difference.
I will let it go and accept the 97 mA rest current.
It works good. Cooling is enough, so not really a problem.
Much power for my piano and organ with only 2 x 19 V. That was my aim.

But it is a little bit strange that it is more than the 85mA max and 50 mA typ. of the TI specs .....