Help with understanding TDA8425 volume control

[sarge]

Hi,
That is truth table volume control from datasheet on tda8425


I don't understand this logic:
-64 dB - 0bxx011100
-62 dB - 0bxx011101
-60 dB - 0bxx011110
-58 dB - 0bxx011111
.....
4 dB - 0bxx111101
6 dB - 0bxx111111

And what number should be for -56 dB?
Maybe this error in second and third bits?

Thanks

 

[sky_123]

seems pretty straightforward: since 6dB is 63decimal according to the truth table and it says 2dB per step,
then -56dB will be 63-((6+56)/2) = 32dec.
With 6 bits, the addresable range is 128dB, but the dynamic range of the IC doesn't extend that far, hence the
table just says <-80 for the lower numbers.

 

[sarge]

Thanks a lot, I understood this logic!