Coolaudio V2164 / Analog devices SSM2164 control voltage question

[tss]

The device is capable of +20dB amplification and +100dB attenuation. I can't find in the datasheet the needed control voltage to control it. For example if I am running on 4.5V (low) and 9V (high), at 4.5V it's 0dB but what's from there?

http://www.coolaudio.com/docs/datasheet/V2164MD_DATASHEET.pdf

[tss]

bump... anyone?

[slacker]

According to the data sheet its -33mV/dB, so -100dB would be 3.3 volts and +20 dB would be -0.66 volts?
That's relative to ground or 1/2 the supply if you're running on a single supply.

[ianhattwick]

If you look at the test circuit on page 7 of the datasheet VC is set by a voltage divider between +8 and ground. Maybe try that circuit and see how it works?

[ElectricDruid]

I've played with this chip quite a bit, and Slacker's right. The response for attenuation goes from -100dB at 3.3V to 0dB at 0V. If you carry on down you get 20dB with -0.66V.

Although this can seem like it's 'the wrong way up', it's often driven from an inverting op-amp mixed several sources, so it turns out quite handy.

I usually use a pot between 3.3V and 0V to test these chips. The 3.3V rail probably has a processor running on it, so I'm mixing analog and digital (Arggh! Unholy!!) but it's only for testing, right?

It's a great chip. Makes lovely filters, but you can do *anything* else with it too. AD should keep it, poor deluded fools.

Tom