volume/output power control using a knob in TAS5424C-Q1

[arunkumar413]

Hi Folks,

It seems that the gain in the IC TAS5424C-Q1 can be controlled using I2C protocol. But I'd like to keep it simple using a hardware (rotatory knob). Is it possible to control the volume and output power using hardware control such as a rotatory knob generally used in car head units.

Thanks,
Arun

 

[Les Jones]

You could use a potentiometer connected to the ADC input of a microcontroller which could convert the voltage reading into I2C data to control the gain of the TAS6424C-Q1 A PIC12F1840 would probably do the job.

Les.

 

[arunkumar413]

The IC has analog inputs. How about using a resistor divider network to control the voltage to the analog input pins. Or vary the supply the voltage?

 

[Nigel Goodwin]

There's no need to use the analogue inputs, simply use a microcontroller to read a rotary encoder (as used in car radios) and control the I2C bus from the microcontroller.

You 'could' use an analogue pot (directly across the supply lines, with a series resistor from slider to analogue input), but an encoder is 'nicer'

 

[Les Jones]

I had not looked at the data sheet before my first reply. After looking at the data sheet it looks like the I2C control is just to select 4 preset gain values. (12, 20, 26 or 32 db) This would not be enough to use for a volume control. The only analogue inputs I can see are the audio inputs so you could just use a normal dual log potentiometer for volume control. Trying to control the gain by adjusting the supply voltage is a bad idea. It would result in clipping which would cause distortion.

Les.

 

[arunkumar413]

The audio input would be from a 3.5 mm TRSS jack of a mobile. Will the potentiometer solution be reliable in this scenario. I don't think there is a graph in the datasheet to show the analog input and output voltage. Also if we go with the analog control would be internal gain in the register set to by default?