PGA2311 volume control.

[ian332isport]

Good evening.

I'm currently working on a project that uses a PGA2311 volume control chip. I've got it all hooked up and controlled by an Arduino and is actually working really well.

I'm currently at the point where I need to connect it to an amplifier (in my case a car amplifier - Mosconi AS100.4). My problem is that I don't know if I can connect the output from the PGA2311 directly to the input of the amplifier, or if I need some sort of buffer amplifier.

Reading the PGA2311 datasheet, it states that it can drive 600 ohm loads directly. The only spec I can find on the amplifier states that it has an 11 Kohm input impedance. I'm guessing that this is going to be an issue. I'm quite new to electronics and I'm possibly getting confused between resistance and impedance, so I'd appreciate it if someone can give me some guidance.

if it helps, you can find the amplifier datasheet here:

http://mosconi-system.it/wp-content/uploads/2014/04/Specifications_AS100.4_2014.02.pdf

Many thanks,

Ian.

 

[udok]

Hello,
It's ok to connect the PGA2311 with a short cable to the car amplifier. Impedance and Resistance is the same in this case.
Greetings,
Udo

 

[ian332isport]

Hello,
It's ok to connect the PGA2311 with a short cable to the car amplifier. Impedance and Resistance is the same in this case.
Greetings,
Udo

Hi Udo,

Thanks for the reply.

If Impedance and Resistance are the same in this case, how can the PGA2311 drive an 11Kohm load when the datasheet states 600ohm max ?

Thanks,

Ian.

 

[wintermute]

Think of it this way. The lower the resistance the more current will flow. If you go below 600 ohms impedance then the opamp will need to deliver more current (which it isn't designed for. so Max load is 600 ohms. ie a lower impedance of say 300 ohms will require more current and thererfore be a higher load!

Does that clear things up?

Tony.

 

[ian332isport]

Hi Tony,

That clears it up perfectly

I was looking at it the wrong way round.

Many thanks,

Ian.