RT5509WSC datasheet(20/58 Pages) RICHTEK

20 / 58 page

RT5509

is a registered trademark of Richtek Technology Corporation

www.richtek.com

DS5509-00

August

2017

Pass-Through Mode

There is pass-through mode for debug or application

use.

SPKE = 0 viewed as DSP through mode, where the

signal is processed by DSP then passed through

volume and amplifier.

Set SPKE = 1 to the normal mode, all functions are

turned on regardless of the setting of DSPE.

Pilot is always disabled if SPKE = 0.

Audio Effect DSP Functions

10-BiQuad

After

channel

selection,

there

are

fully

programmable

bi-quad

filters

implemented

for

user-specified frequency response. The coefficients

are 24-

bit 2’s complement numbers, which are set by

I2C interface.

Band-Split & BWE

Dedicated

HPF/LPF

with

programmable

corner

frequency are equipped after 10-Biquad filters, both are

implemented by selectable 1st or 2nd order Butterworth

filter.

LPF is only needed when optional BWE is enabled.

The BWE block generate harmonic terms to recover

the suppressed of low-frequency signal that is not

efficiently conveyed on small loudspeaker.

All the HPF/LPF/BWE functions can be bypassed.

Dynamic Range Control (DRC)

DRC is a specific feature to automatically adjust the

volume gain corresponds to different input signal. With

DRC function, the output dynamic range is under

controlled from input amplitude is unknown or varies

over a wide range. The RT5509 provide three

thresholds as dynamic range compression (DRC_TH0),

extension (DRC_TH1) and Noise Gate. For the

application of compression and extension, the slope

ratio can be programmed as R0 and R1, respectively.

Input Level (dB)

Dynamic

Range

Expander

Compressor/Limit

Noise Gate

Compressor rate

Figure 14. Dynamic Range Control

DRC function is composed of several parts as following

Figure.

The

input

signal

passes

through

the

programmable Energy Filter (DRC_AE). The Filter

structure is shown in Figure 15. The time constant of

each filter can be determined by below equation :

window

-1

f In (1 - ae)

Then, the filtered signal is compared with the given

compression threshold. After the comparison between

Input signal amplitude and threshold, the Attack Rate

(DRC_AA) determines how quickly the DRC gain

decreases when the signal amplitude is high. The

Decay Rate (DRC_AD) determines how quickly the

DRC gain increases when the signal amplitude is low.

RT5509WSC Datasheet(PDF) 20 Page - Richtek Technology Corporation

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