KJBob

Sigma 300 (ADAU145x) Slew Volume Rates

Discussion created by KJBob on Nov 24, 2014
Latest reply on Nov 16, 2016 by matthijs

     Slew volume controls can filter noisy control inputs and minimize clicks.  Often the desired slew rate can be found by experiment.  However, in some applications it would help to know the actual slew rate a given setting yields.  For example, the ADAU1701's slew rates are described at https://ez.analog.com/message/156092#156092

 

Slew-rate-1452-block_pic.png    The -1452's slew volume controls are different (and more versatile) than those of older SogmaDSPs,  There's separate rise and fall settings, each with several curves to choose from.  The "RC" curve setting shown here provides slewing similar to that of the older slew volume blocks, thus the slew rates can be measured the same way (see the post cited above).  Although this RC curve is exponential in nature (it follows the RC characteristic that includes the term e^(-t/RC), the -1452 slew block also offers a separate exponential choice. Testing the -1452's RC slewing this way results in the table below.  Slew times are given as a time constant as well as the dB/s rate often specified for SigmaDSP dynamics processors.

 

Slew-rate-1452-RC-results_pic.png

The Sigma 300's Exponential slewing operates in ways both similar to, and different from, the RC slewing.  The post at Sigma 300 (ADAU145x) Exponential Slewing describes the differences.



Slew-rate-1452lin-results_pic.png

 

 

 

 

 

    Linear slew settings yield these 10 -- 90 % rise and fall times.  If you prefer 0 -- 100 % times, multiply these times by 1.25..

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