RT5508 datasheet(22/57 Pages) RICHTEK

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RT5508

is a registered trademark of Richtek Technology Corporation

www.richtek.com

DS5508-01

March

2017

(seconds)

InitUpDoubleTime[7:0] : gain double time used for

signal just detected from silence mode.

UpDoubleTime, DnHalfTime, InitUpDoubleTime and

InitDnHalfTime are unsigned 8-bit number representing

the value 1/16~15.9375, 0x10 is normalized to 1.

ALCInitGain[2:0] : ALC initial gain when signal is

detected from silence mode. 0 ~ 21dB, 3dB step.

ALCMaxGain[2:0] : ALC maximum allowable gain. 0 ~

21dB, 3dB step.

Gain

DnFlag

DnFlag==1

ALC_period expired??

yes

sPeak>sThres ||

xPeak>xThres ||

DCR>rThres

yes

Gain = ALCInitGain

PWDN/SUSPD/Off/F

ault/Mute

/SilenceReset

PWDN/SUSPD/Off/F

ault/Mute

/SilenceReset

DnFlag = 0

Figure 17. Gain Generation for ALC

Gain Limiter

The signal and excursion is limited to ensure the signal

is not clipped, and the excursion never growth over the

maximum allowable value.

The gain required to limit the signal and excursion are

calculated by :

Lmt

sThres

xThres

= min

sPeak

xPeak







The parameters for Limiter control :

sThresLmt : Threshold of signal, specified by 0 to 1. 1

corresponds to the maximum allowable signal specified

by clipper module.

xThresLmt : Threshold of excursion, specified by 0 to 1.

1 corresponds to the maximum allowable excursion.

xThresLmtDamage : Threshold of excursion when

either resistance or excursion damage is detected.

DC Resistance Control Loop

DC Resistance Measurement

Metal coil resistance is highly linear dependent on the

temperature, for example the scale factor is +0.393%/C

for copper. The coil resistance is online monitored by

the speaker protection algorithm. The update is

disabled at PWDN/SUSPD/Off/Fault/Mute mode. A

monitored or not in Silence mode.

The parameters for Coil Resistance :

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