LM13600 Unused pins?

[Arn C.]

I am using a LM13600 IC and I am only using half of it for the project I am working on. 
Would I have to ground any of the remaining inputs?

This is what I am not using:
Pin 9  Buffer output
Pin 10 Buffer Input
Pin 12 Output
Pin 13 Input(-)
Pin 14 Input(+)
Pin 15 Diode Bias
Pin 16 Amp Bias Input

Thanks
Arn C.

[frequencycentral]

No need to!

[Arn C.]

Thanks!!!!!!!

Arn C.

[Cliff Schecht]

While it doesn't hurt to leave those pins floating, it's usually a good idea to ground the inputs to prevent oscillation. This includes both plus and minus inputs as well as the buffer input.

Also, to note, I've blown out quite a few OTA's by leaving the Iabc pin floating with power and signals running through. The floating pin will cause excessive current to flow through the output and will fry the bugger (the outputs aren't rated for much current).

[gez]

While it doesn't hurt to leave those pins floating, it's usually a good idea to ground the inputs to prevent oscillation. This includes both plus and minus inputs as well as the buffer input.

If there's no Iabc connection, and none of the other pins are connected/used (no input signal), how can it oscillate?  Not being a smart arse (genuine question in case I'm missing something).

[Arn C.]

Looking at the data sheet I sort of see what you mean Gez .   The only thing common for both sections is the V+  which ties to both buffer inputs and outputs.
And of course V-  . 

It's early and I don't know what the heck I am talking about..........................

Peace!
Arn C.

[gez]

It's early and I don't know what the heck I am talking about..........................

The story of my life! 

[Arn C.]

Thanks Cliff !!!

Thanks Gez 

[R.G.]

Grounding Iabc is a positive "off" measure. It forces the internal current sources to be zero, and makes the amplifier good and solidly not active.

[Arn C.]

Maybe a stupid question, but , what is Iabc?  If I was to ground this, what pin is it?

Thanks!
Arn C.

[frequencycentral]

Maybe a stupid question, but , what is Iabc?  If I was to ground this, what pin is it?

Thanks!
Arn C.

The unused pin 1 or 16, depending upon which side you aren't using.

[Arn C.]

Amp Bias Input  = Pin 16

So, then I can disregard grounding: 

Pin 10 Buffer input
Pin 13   - input
Pin 14   + input


Thanks!
Arn C.

[gez]

If my memory serves me well (which it doesn't these days!)

abc = Amplifier Bias Current

[Cliff Schecht]

While it doesn't hurt to leave those pins floating, it's usually a good idea to ground the inputs to prevent oscillation. This includes both plus and minus inputs as well as the buffer input.

If there's no Iabc connection, and none of the other pins are connected/used (no input signal), how can it oscillate?  Not being a smart arse (genuine question in case I'm missing something).

Well, typically, they won't oscillate. In some weird fluke that one manages to couple some noise into the input (either from the output or other sources), surrounded by a lot of stray resistance/capacitance/inductance, I would think that there is an ability for the circuit to oscillate though. The inherently high gain nature of the input diff amp with no emitter degeneration (i.e. a floating Iabc pin) could cause oscillation, even if it's out of audible frequency. Grounding at least the Iabc pin (through a resistor) would prevent any voltage from developing at the output and will prevent most any problems. Maybe I'm just too cautious though, I don't think I've ever had a 13700 actually self-oscillate.

This is more of a problem with op amps, where a floating input pin combined with a high open-loop gain and parasitic resistances/capacitances/inductances can cause oscillation problems.

I think he's safe just grounding that Iabc pin through 10k resistor.

[Arn C.]

Thank you Cliff and everyone for your help on this!

Peace!
Arn C.