LM3886 Standby

Moze

Member
2012-12-02 11:40 pm
Hi all - LM3886 has a mute function but not standby like the TDA729x...Does anyone have a method for putting the amp chips into a low or no power mode when not in use such as in a 5channel config for HT but you are using only 2 channels...I see no reason to keep 3 or 4 watts dissipating from the other 3 chips...My only ideas are one of the following:

1. Install a DPDT switch that connects V+ and V- from the IC...crudest method I can think of but does constant power on and off cause any harm?

2. Circuit that detects an input signal and powers on the amp if signal is detected similar to subwoofer amps
 

tomchr

Member
Paid Member
2009-02-11 12:58 am
Calgary
www.neurochrome.com
I bet it pulls 100mA or so idle, no big deal.

50 mA, typical. 85 mA worst case according to the data sheet.

No harm will be done by "constant" ON/OFF switching but why would you do that on a continuous base?

Why burn the power if you don't need it?

I haven't tried this, but the 3886 has a slow start pin

Um. No. It has a mute pin. It's not a slow start pin. It just switches the bias current from the main input pair to the mute pair.

I think it may operate a current source that will effectively shut down the output section somehow, thereby reducing current draw to a minimum.

Nope. It doesn't. See the equivalent circuit on Page 7 of the LM3886 data sheet. I describe the functionality in a bit more detail on my taming the LM3886 pages.

Tom