Datasheet

STA309A Registers
Doc ID 13855 Rev 4 29/67
7.2.6 Configuration register F (0x05)
The STA309A features an internal digital high-pass filter for the purpose of AC coupling. The
purpose of this filter is to prevent DC signals from passing through a DDX amplifier. DC
signals can cause speaker damage.
If HPB = 1, then the filter that the high-pass filter utilizes is made available as user-
programmable biquad#1.
Both limiters can be used in one of two ways, anti-clipping or dynamic range compression.
When used in anti-clipping mode the limiter threshold values are constant and dependent on
the limiter settings.
In dynamic range compression mode the limiter threshold values vary with the volume
settings allowing a nighttime listening mode that provides a reduction in the dynamic range
regardless of the volume level.
By setting this bit to one de-emphasis will implemented on all channels. When this is used it
takes the place of biquad #7 in each channel and any coefficients using biquad #1 will be
ignored. DSPB (DSP bypass) bit must be set to 0 for de-emphasis to function.
D7 D6 D5 D4 D3 D2 D1 D0
PWMS2 PWMS1 PWMS0 BQL PSL DEMP DRC HPB
00000000
Table 27. HPB bit
Bit RW RST Name Description
0RW 0 HPB
High-pass filter bypass bit:
1: bypass internal AC coupling digital high-pass filter
Table 28. DRC bit
Bit RW RST Name Description
1 RW 0 DRC
Dynamic range compression/anti-clipping:
0: limiters act in anti-clipping mode
1: limiters act in dynamic range compression mode
Table 29. DEMP bit
Bit RW RST Name Description
2RW 0 DEMP
De-emphasis:
0: no de-emphasis
1: de-emphasis