MSM7731-02 OKI [OKI electronic componets], MSM7731-02 Datasheet - Page 48

• Manufacturer Part Number: MSM7731-02
• Description: Dual Echo Canceler & Noise Canceler with Dual Codec for Hands-Free
• Manufacturer: OKI [OKI electronic componets]

NOTES ON USE
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10. Adjust the volume at the position of the echo canceler input (RinA/RinL).
11. When the echo path is changed (when resuming telephone communication), reset the device with the RST pin
12. After turning on the power, be sure to reset the device with the PDN/RST pin or the PDN/RST bit.
13. In order to get the highest performance of this device, the following functions should be used.
1 Semiconductor
Use a stabilized power supply with a low level of noises (especially spike noises and pulse noises of high
frequencies) in order to prevent this device from malfunction or degradation in characteristics.
Place a good characteristic of bypass-capacitor for the power supply near the pins of this device in order to
assure its electrical characteristics.
Place a good characteristic of bypass-capacitor for the analog signal ground (SG pin) near the pins of this
device in order to assure its electrical characteristics.
Connect the AGND, DGND1 and DGND 2 to the system ground at a shortest distance and in a low
impedance state.
Use a separate power supply for an external speaker amplifier so as not to be disturbed by externally
generated noises.
When an external speaker amplifier is used, do gain adjusting without overflow (saturation) of speaker
amplifier output.
The overflow of speaker amplifier output decreases the echo attenuation.
Set the analog signal input level to less than 1.3 V
Otherwise, voice will be distorted.
Set the echo return loss (ERL) to be attenuated. If the echo return loss is to be amplified, the GLPAD function
should be used.
The ERL refers to echo attenuation (loss) between the echo canceler output (RoutA/RoutL) and the echo
canceler input (SinA/SinL).
Refer to Characteristics Diagram for the ERL vs. echo attenuation.
The input level should be –10 to –20 dBm0.
Refer to Characteristics Diagram for the ERL vs. echo attenuation.
or the RST bit.
When in Dual Echo Canceler mode
When in Signal Echo Canceler mode
AATT/LATT
AGC/LGC
SLPTHR
NCTHR
RPAD6-1
TPAD6-1
: ON
: ON
: Normal mode (slope filter operation)
: Normal mode (noise canceler operation)
: Adjusting the volume of receive signal
: Adjusting the volume of transmit signal
: Adjust the volume with TPAD and RPAD.
: Adjust the volume with TPAD and RPAD, or with the analog
input (LIN) that is set at less than 1.3 V
PP
to prevent overlow.
PP
.
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