digital volume pot ic

Bengali · 13th March 2007, 06:12 PM

Hi,

I'm working with a Maxim 5456 10K digital pot.

Everything is functional however I'm getting major
distortion in the audio.

I'm wiring it in place of a standard pot, H end (input),
Wiper(output), L end to GND. it's between the cd player's
output and a preamp.

any suggestions as to what I may be doing wrong?

thanks

paulb · 13th March 2007, 06:21 PM

You probably need an op-amp buffer as it shows in the data sheet.

Bengali · 13th March 2007, 06:35 PM

thx. guess I will try an op amp next.

do you know why they have the low end tied to Vdd/2, half of Vdd? instead of to Gnd? this wiring is for their headphone amp.

paulb · 13th March 2007, 06:58 PM

It's because it is a single-supply device and the signal has to be referenced to a point in the middle of the supply voltage so the device can swing above and below it. This is similar to using an op-amp with a single supply voltage: you need a reference voltage somewhere in the middle. You're probably hearing what it sounds like with only the positive swings. clipping everything below 0.

Bengali · 13th March 2007, 07:01 PM

ah! makes sense. thanks. will proceed with an op amp.

13th March 2007, 06:12 PM	#1
Bengali diyAudio Member Join Date: Oct 2006	digital volume pot ic Hi, I'm working with a Maxim 5456 10K digital pot. Everything is functional however I'm getting major distortion in the audio. I'm wiring it in place of a standard pot, H end (input), Wiper(output), L end to GND. it's between the cd player's output and a preamp. any suggestions as to what I may be doing wrong? thanks

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13th March 2007, 06:21 PM	#2
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	You probably need an op-amp buffer as it shows in the data sheet.

13th March 2007, 06:35 PM	#3
Bengali diyAudio Member Join Date: Oct 2006	thx. guess I will try an op amp next. do you know why they have the low end tied to Vdd/2, half of Vdd? instead of to Gnd? this wiring is for their headphone amp.

13th March 2007, 06:58 PM	#4
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	It's because it is a single-supply device and the signal has to be referenced to a point in the middle of the supply voltage so the device can swing above and below it. This is similar to using an op-amp with a single supply voltage: you need a reference voltage somewhere in the middle. You're probably hearing what it sounds like with only the positive swings. clipping everything below 0.

13th March 2007, 07:01 PM	#5
Bengali diyAudio Member Join Date: Oct 2006	ah! makes sense. thanks. will proceed with an op amp.

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