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### Topic: LM1876 mute function (Read 1 time)previous topic - next topic

#### dataplex

##### Jan 11, 2013, 08:41 pmLast Edit: Jan 11, 2013, 08:43 pm by dataplex Reason: 1
hey guys

a very simple question;

i am waiting for my arduino MEGA to arrive in a few days.

i need to switch a bunch of LM1876's op amps on/off. they have mute pins that mute the signals passing through by receiving 5v!

so i figured i could use the arduino pins to switch the array of amps on/off.

however, my question is - do i need to put some kind of resistors inbetween or something to avoid drawing too much power/frying my arduino while muting 10+ LM1876's??

i should add, by default ALL AMPS WOULD BE MUTED AT THE SAME TIME - meaning id continuously be sending 5v through at least 10+ pins most of the time.

datasheet for the LM1876 can be found here :: http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=snas097b&fileType=pdf

any thoughts would be greatly appreciated!

thanks,
Ășlfur
-------http://ulfurhansson.com/

#1
##### Jan 11, 2013, 11:39 pm
Looked through datasheet and I read that the Mute function has a max of 2.5V not 5V.  It also did not say how much current it would pull, unless I missed it somewhere.  I would put the 2.5V to the circuit to produce the Mute and measure the current.

The absolute maximum current rating per pin is 40mA, but it's safer to not go over 30mA.

#### Magician

#2
##### Jan 12, 2013, 01:28 am
Looking at page 17 Figure 7, 100 k resistor in series with mute, I'd estimate input current about 100 - 300 uA, so there is no issue to drive 100 input with 1 arduino pin. Read text on p.17, if you gonna use single rail power supply.

#### dataplex

#3
##### Jan 12, 2013, 03:47 am
@magician thanks! im using a split power supply, so that wont be a problem. 100kresistors it is then...
-------http://ulfurhansson.com/

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