CDB6420 Ver la hoja de datos (PDF) - Cirrus Logic

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CDB6420

Full-Duplex Speakerphone Chip

Cirrus Logic 

CDB6420

AFNse - Acoustic Full-duplex Noise threshold

zero:

-42 dB:

-54 dB:

use AErle as sole criterion to transition to full-

duplex.

echo path may not exist, so go to full-duplex

when noise level is below -42 dB (easy) and in-

ternal determination of path/no path is complete

echo path may not exist, so go to full-duplex

when noise level is below -54 dB (hard) and in-

ternal determination of path/no path is complete

PCSen - Path-Change Sensitivity

high:

low:

more sensitive to near end path changes (on rare

occasions may briefly drop into half-duplex

during doubletalk)

less sensitive to path changes and more robust

to doubletalk

GB - Graded Beta

0.00 dB/ms: use to disable beta grading

0.75 dB/ms: use for acoustically dead rooms (e.g. inside a

car)

0.38 dB/ms: use for "typical" rooms

0.19 dB/ms: use for very acoustically live rooms (e.g. glass

or tile walls, no carpet, etc.)

Taps - allocation of filter Taps

55.5ms/---: allocate all taps to Acoustic canceller (disables

Network canceller)

47.5ms/16ms:use for short Network path echo durations or

for longer Acoustic path

38.5ms/24ms:use for typical Network path echo durations

31.5ms/32ms:use for long Network path echo durations (note

that Acoustic performance may suffer)

TSD - Transmit Suppression Disable

checked: disable transmit suppression

unchecked enable transmit suppression

TSThd - Transmit Suppression Threshold

15 dB:

12 dB:

9 dB:

need 15 dB ERLE at acoustic canceller to dis-

criminate between speech and echo

less sensitive to near end speech (more prone to

suppressing near-end speech)

least sensitive to near end speech (most prone to

suppressing near-end speech)

TSAtt - Transmit Suppression Attenuation level

18 dB:

12 dB:

24 dB:

default

use if noise modulation caused by suppression

is annoying and residual echo is not perceptible

use if residual echo after suppression is percep-

tible

TSBias - Transmit Suppression Bias

18 dB:

15 dB:

21 dB:

default

harder for near end to break in. See CS6420

datasheet for details

easier for near end to break in. See CS6420

datasheet for details

TGain - Transmit ADC analog Gain

0 dB, 6 dB, 9.5 dB, 12 dB:

set gain of the ADC at API/APO

Mic - Microphone preamplifier select

API:

APO:

ADC input is taken from API/MICIN through

34 dB amplifier (HDR1 on board must be set to

PREAMP ON)

ADC input is taken from APO/APO_IN (HDR1

on board must be set to PREAMP OFF)

Reset Button

Cold Reset, Default:

cold reset to default register values

Warm Reset, Default:

warm reset to default register values

Cold Reset, Current:

cold reset to register values indicated by con-

trols

Warm Reset, Current:

warm reset to register values indicated by con-

trols

Power Down:

hold CS6420 RST low to force low power

mode

Power Up, Cold Reset, Current:

bring CS6420 RST high; restore register values

indicated by controls

Power Up, Warm Reset, Current:

bring CS6420 RST high; warm reset and re-

store register values indicated by controls

48

DS205DB1

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