Cirrus Logic CS44600 - Manual (Page 60)

60 DS633F1
CS44600
7.17 Limiter Release Rate (address 17h)
7.17.1 Release Rate (RRATE[7:0])
Default = 00100000
Function:
The limiter release rate is user selectable. The effective rate is a function of the SRC output sampling fre-
quency and the value in the Release Rate register. Rates are calculated using the function
RATE = (512/{value})/SRC Fs, where {value} is the decimal value in the Release Rate register and SRC
Fs is the output sample rate of the SRC which is determined by the PWM master clock frequency. SRC
Fs equals 384 kHz for 24.576 MHz based clocks and 421.875 kHz for 27.000 MHz based clocks.
Note: A value of zero in this register is not recommended, as it will induce erratic behavior of the limiter.
Use the LIM_EN bit to disable the limiter function (see
Peak Limiter Control Register (address 15h) ).
7.18 Chnl XX Load Compensation Filter - Coarse Adjust
(addresses 18h, 1Ah, 1Ch, 1Eh, 20h, 22h)
7.18.1 Channel Compensation Filter - Coarse Adjust (CHXX_CORS[5:0])
Default = 000000
Function:
The Channel Load Compensation Filter Coarse Adjustment settings control the amount of attenuation of
this single-pole filter and are used in conjunction with the Fine Adjustment bits to compensate for speaker
impedance load variations. Each PWM channel is controlled by an associated register. The coarse ad-
justment bits will attenuate the audio response curve according to the table below in 0.1 dB increments.
Filter setting values less than -4.0 dB will cause the PWM output to mute.
Binary Code Decimal Value Attack Rate - 384 kHz
(µs per 1 /
8
dB)
Attack Rate - 421.875 kHz
(µs per 1 /
8
dB)
00000001 1 83.33 75.852
00010100 20 4.167 3.793
00101000 40 2.083 1.896
00111100 60 1.389 1.264
01011010 90 0.926 0.843
Table 10. Limiter Attack Rate Settings
7 6 5 4 3 2 1 0
RRATE7 RRATE6 RRATE5 RRATE4 RRATE3 RRATE2 RRATE1 RRATE0
Binary Code Decimal Value Release Rate - 384 kHz
(µs per 1 /
8
dB)
Release Rate - 421.875 kHz
(µs per 1 /
8
dB)
00000001 1 1333.333 1213.630
00010100 20 66.667 60.681
00101000 40 33.333 30.341
00111100 60 22.222 20.227
01011010 90 14.815 13.485
Table 11. Limiter Release Rate Settings
7 6 5 4 3 2 1 0
RESERVED RESERVED CHXX_CORS5 CHXX_CORS4 CHXX_CORS3 CHXX_CORS2 CHXX_CORS1 CHXX_CORS0