MITSUMI
Compander IC MM1077
Compander IC
Monolithic IC MM1077
Features
This IC was developed for use in cordless telephone equipment. It is a compander IC incorporating
compressor/expander circuits for a significant noise reduction effect without complicated external circuitry.
On the transmission side, the dynamic range of audio signals is compressed by the compressor circuit; on the
receiving side, the expander expands the signals. As a result the dynamic range over the transmission
channel is reduced logarithmically by one-half.
1. Can be driven at low voltages (down to 2.0V)
2. Internal mute function
3. Internal limiter (IDC) function
4. Compressor input can be switched between MIC and LINE
5. Internal standby function
6. Data input, output pins
7. Independent mute circuit
Package
SSOP-24A (MM1077XF)
Pin Assignment
SSOP-24A
1
3
6
9
2
4 5
8
7
10
12
11
24
20
17
23
21
19 18
16
22
13
14
15
Applications
1. Cordless telephones
2. Various mobile communication devices
1
C.Vref
9
DATA. IN
17
E.RECT
2
C.IN1
10
C.CONT
18
E.OUT
3
C.IN2
11
N.C
19
E.RIN
4
C.IN-
12
GND
20
A.OUT
5
C.RECT
13
STANDBY SW
21
A.IN-
6
C.RIN
14
C.IN SW
22
A.IN+
7
C.FB
15
C.MUTE SW
23
E.Vref
8
C.NF
16
E.MUTE SW
24
Vcc
Outline
MITSUMI
Compander IC MM1077
Block Diagram
Absolute Maximum Ratings
(Ta=25
C)
Item
Symbol
Ratings
Units
Storage temperature
T
STG
-40~+125
C
Operating temperature
T
OPR
-10~+70
C
Power supply voltage
V
CC
max.
-0.3~+8
V
Allowable loss
Pd
650
mW
Operating voltage
+2.0~+7
V
MITSUMI
Compander IC MM1077
Electrical Characteristics
(Except where noted otherwise, Ta=25
C, V
CC
=3V, fin=1kHz)
Function Description
Item
Symbol
Measurement conditions
Min. Typ. Max. Units
Consumption current
I
CC
No signal
4.0
6.0
mA
Standby current consumption
Iscc
0
10
A
Threshold voltage
Vth
0.40
0.65
0.80
V
Input reference level
V
IN
c
Voc=100mVrms, V
IN
=0dB
8.0
13.5
18.0 mVrms
Gain error
*
Gc1
V
IN
=-20dB
-0.5
0
0.5
dB
Gc2
V
IN
=-40dB
-1.0
0
1.0
dB
Distortion
THDc
V
IN
=0dB
0.3
1.0
%
Output noise voltage
Vnc
No signal (CCITT)
2.5
5.0
mVrms
Mute attenuation
Attc
V
IN
=0dB, C.MUTE SW : ON
40
50
dB
Limit voltage
Vlimc
THD=10%
700
800
900
mV
p-p
DATA pin voltage gain
G
DATA
C. MUTE SW : ON, V
IN
=0dB -0.5
0
0.5
dB
DATA pin maximum output
VD max. C.MUTE SW : ON, THD=10% 800
900
mVrms
Crosstalk
CTc
EXPV
IN
=0dB
28
33
dB
Ripple rejection ratio
RRc
V
R
=100mVrms, f
R
=1kHz
18
23
dB
Input reference level
V
IN
e
Voe=100mVrms, V
IN
=0dB
25
35
50
mVrms
Ge1
V
IN
=-10dB
-0.5
0
0.5
dB
Gain error difference
*
Ge2
V
IN
=-20dB
-1.0
0
1.0
dB
Ge3
V
IN
=-30dB
-1.5
0
1.5
dB
Distortion
THDe
V
IN
=0dB
0.15
1.0
%
Maximum output voltage
Ve max.
THD=10%
600
800
mVrms
Output noise voltage
Vne
No signal (CCITT)
20
40
Vrms
Mute attenuation
Atte
V
IN
=0dB, C. MUTE SW : ON
60
70
dB
Input amp voltage gain
GI
V
IN
=0dB
14.6
15.6
16.6
dB
Input amp maximum output
Veo max.
THD=10%
0.90
1.10
Vrms
Crosstalk
CTe
COMPV
IN
=0dB
60
75
dB
Ripple rejection ratio
RRe
V
R
=100mVrms, f
R
=1kHz
50
60
dB
Compressor
unit
Expander
unit
1. Compressor unit
The compressor unit consists of the mike amp, compressor, limiter circuit, data amp, and mute circuit.
The mike amp gain can be adjusted through an external resistance, and so the mike amp can be
connected directly to a microphone. An internal limiter circuit to prevent overmodulation as well as a data
amp (0dB amp) enabling transmission of data signals without compression are also provided. Switching
between audio signals and data signals is possible using the compressor mute switch.
2. Expander unit
The expander unit consists of an input amp, expander, and mute circuit.
The input amp makes available all input and output signals at pins, and so can be used freely as an
amplifier, filter amp, or data amp. When used as a data amp, the expander mute switch can be set so that
the expander output is nearly silent.
*
Gain error difference = (V
OUT
(dBv)+20dB) -V
IN
(dB) G (dB)
G : COMP=0.5, EXP=2
MITSUMI
Compander IC MM1077
About Application Circuits
The compressor unit mike amp is exposed to circuits outside the IC via positive and negative input pins.
The positive input pin is connected to C.Vref by a bias resistance of 100k
, so that no external bias is
needed.
When pin 4 is open the gain is lowest, and an input voltage of approx. 13.5Vrms is the reference level.
When the external resistance is 0
, the gain is maximum. The internal configuration appears in Fig. 1.
1. Mike amp
The product of the external capacitance and the internal resistance (10k
) determines the time constants
for the attack and release times.
2. Rectifier circuit unit (rectifier)
The compressor amp requires that the DC gain be unity and the AC gain be infinite. In order to satisfy this
requirement, AC feedback is eliminated and only DC feedback is used. In order that only DC feedback be
present, a capacitor to eliminate AC components is connected to pin 8. The cutoff frequency is determined
by the product with the internal resistance (100k
).
3. Compressor amp
MITSUMI
Compander IC MM1077
The data amp uses an inverting amp. The internal input resistance is 100k
, and the DC bias voltage is
1.3V. The compressor mute switch at pin 15 is used to switch between data signals and audio signals.
4. Compressor data amp
The positive and negative input pins and the output pin are exposed to circuitry outside the IC. The
expander input amp can be used as a signal amplifier, a buffer amplifier, and a filter amp. By taking the
signal from this amp's output pin, the data signal can be obtained without passing through the expander. If
the expander mute switch is turned on, this signal can be prevented from appearing in the expander output.
5. Expander input amp
The internal equivalent circuit for each of these switches appears in Fig. 6.
6. Mike amp input switch and mute switches
The internal equivalent circuit for the standby switch appears in Fig. 7.
7. Standby switch
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