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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¡ Semiconductor
MSM7620
BLOCK DIAGRAM
MSM7620-001 (Single chip only)
RIN
S/P
Non-linear/
Linear
ATT
Gain
Linear/
Non-linear
P/S
ROUT
Howling
Detector
Double Talk
Detector
Power
Calculator
Adaptive
FIR Filter
(AFF)
–
SOUT
RST
PWDWN
P/S
Linear/
Non-linear
Center
Clip
ATT
+
+
Non-linear/
Linear
S/P
SIN
WDT
V
DD
V
SS
Clock Generator
X1/CLKIN
X2 SCKO
MSM7620-011 (Cascade connection or Single chip)
RIN
S/P
Non-Linear
/Linear
Howling
Detector
Double Talk
Detector
SOUT
*RST
*PWDWN
P/S
Linear/
Non-linear
Clock Generator
X1/CLKIN
X2 SCKO
,
Mode Selector
I/O Controller
INT
SYNCO NLP HCL ADP ATT GC
IRLD
SCK SYNC
ATT
Gain
Linear/
Non-linear
P/S
ROUT
PD15 *
PD 0 *
OF1
*
OF2
*
SF1
*
SF2
*
SIN
WDT
V
DD
*
V
SS
*
Power
Calculator
Parallel
I/O Port
Adaptive
FIR Filter
(AFF)
–
Parallel
I/O
Controller
Center
Clip
ATT
+
+
Non-linear/
Linear
S/P
Mode Selector
I/O Controller
INT
*
SYNCO NLP HCL ADP ATT GC MS
IRLD
SCK SYNC
*
*
*
* If the MSM7620-011 is used in the slave mode, only the diagonally hatched blocks and
the pins marked with * are used.
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¡ Semiconductor
MSM7620
PIN CONFIGURATION (TOP VIEW)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32-Pin Plastic SSOP
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
Pin
1
2
3
4
5
6
7
8
Symbol
*
NLP
HCL
ADP
V
SS
ATT
INT
IRLD
Pin
9
10
11
12
13
14
15
16
Symbol
SIN
RIN
SCK
SYNC
SOUT
ROUT
*
V
SS
Pin
17
18
19
20
21
22
23
24
Symbol
*
*
*
X1/CLKIN
X2
*
PWDWN
SYNCO
Pin
25
26
27
28
29
30
31
32
Symbol
SCKO
*
RST
WDT
GC
*
*
V
DD
*: No connect pin
Note:
Pin 26 of the MSM7520 is CKSEL, while that of the MSM7620 is in open state.
It is possible to replace the MSM7520 with the MSM7620.
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¡ Semiconductor
MSM7620
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
64-Pin Plastic SSOP
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Symbol
NLP
HCL
ADP
MS
ATT
INT
*
IRLD
*
SIN
RIN
SCK
SYNC
SOUT
ROUT
V
SS
Pin
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Symbol
*
*
PD0
PD1
PD2
PD3
PD4
PD5
PD6
PD7
PD8
PD9
PD10
PD11
*
*
Pin
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Symbol
PD12
PD13
X1/CLKIN
X2
*
PWDWN
*
SYNCO
SCKO
*
*
RST
WDT
GC
V
DD
V
DD
Pin
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
Symbol
*
*
PD14
PD15
*
SF2
OF1
*
*
*
SF1
OF2
*
V
DD
*
*
*: No connect pin
Note:
Pins 43, 53, and 61 of the MSM7520 are CKSEL, V
DD
, and TST2 respectively. While these
pins of the MSM7620 are in open state, it is possible to replace the MSM7520 with the
MSM7620.
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¡ Semiconductor
MSM7620
PIN DESCRIPTIONS
(1/5)
Pin
32-pin 64-pin
SSOP
2
QFP
1
Symbol
NLP
Type
I
Description
The control pin for the center clipping function. This forces the SOUT
output to a minimum value (FF) when the SOUT signal is below -54
dBm0. Effective for reducing low-level noise.
• Single Chip or Master Chip in a Cascade Connection
"H": Center clip ON
"L": Center clip OFF
• Slave Chip in a Cascade Connection
Fixed at "L"
This input signal is loaded in synchronization with the falling edge of
the
INT
signal or the rising edge of the
RST
signal.
3
2
HCL
I
The through mode control.
When this pin is in the through mode, RIN and SIN data are output to
ROUT and SOUT. At the same time, the coefficient of the adaptive FIR
filter is cleared.
• Single Chip or Master Chip in a Cascade Connection
"H": Through mode
"L": Normal mode (echo canceler operates)
• Slave Chip in a Cascade Connection
Same as master
This input signal is loaded in synchronization with the falling edge of
the
INT
signal or the rising edge of the
RST
signal.
4
3
ADP
I
AFF coefficient control pin. This pin stops updating of the adaptive FIR
filter (AFF) coefficient and sets the coefficient to a fixed value, when this
pin is configured to be the coefficient fix mode.
This pin is used when holding the AFF coefficient which has been once
converged.
• Single Chip or Master Chip in a Cascade Connection
"H": Coefficient fix mode
"L": Normal mode (coefficient update)
• Slave Chip in a Cascade Connection
Fixed at "L"
This input signal is loaded in synchronization with the falling edge of
the
INT
signal or the rising edge of the
RST
signal.
—
4
MS
I
Selection of the Master Chip and slave chip when used in a cascade
connection.
"L": Single chip or master chip
"H": Slave chip
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