CS42L55 datasheet(32/73 Pages) CIRRUS

32 / 73 page

DS773F1

CS42L55

4.7

Limiter

When enabled, the limiter monitors the digital input signal before the DAC modulators, detects when levels

exceed the maximum threshold settings and lowers the master volume at a programmable attack rate below

the maximum threshold. When the input signal level falls below the maximum threshold, the AOUT volume

returns to its original level set in the Master Volume Control register at a programmable release rate. Attack

and release rates are affected by the DAC soft ramp settings and sample rate, Fs. Limiter soft ramp depen-

dency may be independently enabled/disabled using the LIMSRDIS.

Notes:

Recommended settings: Best limiting performance may be realized with the fastest attack and

slowest release setting with soft ramp enabled in the control registers. The CUSH bits allow the user

to set a threshold slightly below the maximum threshold for hysteresis control - this cushions the

sound as the limiter attacks and releases.

The Limiter maintains the output signal between the CUSH and MAX thresholds. As the digital input

signal level changes, the level-controlled output may not always be the same but will always fall within

the thresholds.

Referenced Control

MSTxVOL[7:0].....................

PMIXxVOL[6:0]....................

OFFTIME[2:0]......................

ONTIME[3:0] .......................

FREQ[3:0] ...........................

BEEP[1:0]............................

BPVOL[4:0] .........................

“Master Volume Control: MSTA (Address 18h) & MSTB (Address 19h)” on page 57

“PCMx Mixer Volume: PCMA (Address 12h) & PCMB (Address 13h)” on page 52

“Beep Off Time” on page 54

“Beep On Time” on page 54

“Beep Frequency” on page 53

“Beep Configuration” on page 55

“Beep Volume” on page 55

Referenced Control

Limiter Rates .......................

Limiter Thresholds

LIMSRDIS ...........................

Master Volume Control........

“Limiter Release Rate” on page 62, “Limiter Attack Rate” on page 62

“Limiter Maximum Threshold” on page 60, “Limiter Cushion Threshold” on page 61

“Limiter Soft Ramp Disable” on page 66

“Master Volume Control: MSTA (Address 18h) & MSTB (Address 19h)” on page 57

FREQ[3:0]

...

BPVOL[4:0]

ONTIME[3:0]

OFFTIME[2:0]

BEEP[1:0] =

'01'

BEEP[1:0] =

'10'

BEEP[1:0] =

'11'

SINGLE-BEEP: Beep turns on at a

configurable frequency (FREQ) and

volume (BPVOL) for the duration of

ONTIME. BEEP must be cleared

and set for additional beeps.

MULTI-BEEP: Beep turns on at a configurable frequency (FREQ)

and volume (BPVOL) for the duration of ONTIME and turns off for

the duration of OFFTIME. On and off cycles are repeated until

REPEAT is cleared.

CONTINUOUS BEEP: Beep turns on at a configurable frequency (FREQ) and volume (BPVOL) and remains on

until REPEAT is cleared.

Figure 18. Beep Configuration Options

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