CS44800 datasheet(62/80 Pages) CIRRUS

62 / 80 page

DS632F1

CS44800

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, 24h, 26h)

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

83.33

75.852

00010100

4.167

3.793

00101000

2.083

1.896

00111100

1.389

1.264

01011010

0.926

0.843

Table 10. Limiter Attack Rate Settings

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

1333.333

1213.630

00010100

66.667

60.681

00101000

33.333

30.341

00111100

22.222

20.227

01011010

14.815

13.485

Table 11. Limiter Release Rate Settings

RESERVED

CHXX_CORS5

CHXX_CORS4

CHXX_CORS3

CHXX_CORS2

CHXX_CORS1

CHXX_CORS0

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