STA320 View Datasheet(PDF) - STMicroelectronics
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STA320 Datasheet PDF : 37 Pages
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STA320
By default, all user-defined filters are "pass-thru" where all coefficients are set to 0, except the b0/2 coefficient
which is set to 400000h (representing 0.5)
5.14.23Pre-Scale
The STA320 provides a multiplication for each input channel for the purpose of scaling the input prior to EQ.
This pre-EQ scaling is accomplished by using a 24-bit signed fractional multiplier, with 800000h = -1 and
7FFFFFh = 0.9999998808.
The scale factor for this multiply is loaded into RAM using the same I2C registers as the biquad coefficients and
the bass-management. All channels can use the channel 1 pre-scale factor by setting the Biquad link bit. By
default, all pre-scale factors are set to 7FFFFFh.
5.14.24Post-Scale
The STA320 provides one additional multiplication after the last interpolation stage and the distortion compen-
sation on each channel. This post-scaling is accomplished by using a 24-bit signed fractional multiplier, with
800000h = -1 and 7FFFFFh = 0.9999998808.
The scale factor for this multiply is loaded into RAM using the same I2C registers as the biquad coefficients and
the bass-management.
This post-scale factor can be used in conjunction with an ADC equipped micro-controller to perform power-sup-
ply error correction. All channels can use the channel 1 post-scale factor by setting the post-scale link bit. By
default, all post-scale factors are set to 7FFFFFh.
5.14.25Over-current Post-Scale
The STA320 provides a simple mechanism for reacting to over-current detection in the power-device. When
the ocdetect input is asserted, the over-current post-scale value is used in place of the normal post-scale value
to provide output attenuation on all channels.
The default setting provides 3dB of output attenuation when ocdetect is asserted. The amount of attenuation
to be applied in this situation can be adjusted by modifying the Over-current Post-scale value.
As with the normal post-scale, this scaling value is a 24-bit signed fractional multiplier, with 800000h = -1 and
7FFFFFh = 0.9999998808. By default, the over-current post-scale factor is set to 5A9DF7h. Once the over-
current attenuation is applied, it remains until the device is reset.
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