E2U0038-28-81
¡ Semiconductor
MSM7620
¡ Semiconductor
Echo Canceler
This version: Aug. 1998
MSM7620
Previous version: Nov. 1996
GENERAL DESCRIPTION
The MSM7620 is an improved version of the MSM7520 with the same basic configuration. The
MSM7620 includes following improvements: a modified through mode, timing control of the
control pin input, and a thinner package. The MSM7620 also provides a pin-for-pin replacement
with the MSM7520.
The MSM7620 is a low-power CMOS IC device for canceling echo (in an acoustic system or
telephone line) generated in a speech path.
Echo is canceled (in digital signal processing) by estimating the echo path and generating a
pseudo-echo signal.
Used as an acoustic echo canceler, the MSM7620 cancels the acoustic echo between the loud
speaker and the microphone which occurs during hands free communication, such as on a car
phone or a conference system phone.
Used as a line echo canceler, the device cancels the line echo impedance mismatching in a hybrid.
In addition, a quality conversation is made possible by controlling the level and preventing
howling with a howling detector, double talk detector, attenuation function and a gain control
function, and by controlling the low level noise with a center clipping function.
The MSM7620 I/O interface supports
m-law
PCM. The use of a single chip CODEC, such as the
MSM7543, allows the configuration an economic and efficient echo canceler to be configured.
Note: If the object is to cancel line echo, the use of the MSM7602 is recommended, for the
MSM7602 is provided with a howling detect control pin. In addition, the MSM7602, while having
characteristics equivalent to the MSM7620, is packaged small.
FEATURES
• Handles both acoustic echoes and telephone line echoes.
• Cancelable echo delay time:
MSM7620-001 ................. For a single chip: 23 ms (max.)
MSM7620-011 ................. For a cascade connection (can also be used for a single chip)
Master chip: 23 ms (max.)
Slave chip: 31 ms (max.)
Cancelable up to 213 ms (one master plus six slaves)
For a single chip: 23 ms (max.)
• Echo attenuation
: 30 dB (typ.)
• Clock frequency
: 18 MHz (36 MHz cannot be used)
External input and internal oscillator circuit are provided.
• Power supply voltage : 5 V (4.5 V to 5.5 V)
• Power consumption
: 150 mW (typ.) When powered down: 20 mW (typ.)
• Package options:
32-pin plastic SSOP (SSOP32-P-640-0.80-K) (Product name : MSM7620-001GS-K)
64-pin plastic QFP (QFP64-P-1414-0.80-BK) (Product name : MSM7620-011GS-BK)
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