MITSUMI
Sensor Amplifier MM1089
Sensor Amplifier
Monolithic IC MM1089
Outline
This IC is an amplifier with a high-impedance differential input, which can be used in high-CMR instrumentation.
Particularly when amplifying signals from a high-impedance or high-bias signal source, often signals are buried
in noise, making amplification difficult. This IC amplifies only the signal, and the noise is suppressed rather than
amplified, making it effective for use where noise is prominent or with high-impedance signal sources.
Features
1. Battery charge/discharge current detection
(for laptops, word processors, etc)
80dB min., 100dB typ.
2. Signal amplifiers for magnetic sensors, pressure sensors, strain gauges
Except 10M
3. Instrumentation amps
3~ 100
4. Broad input range
-0.3V~V
CC
+0.3V
5. Two internal channels
Package
SOP-18A (MM1089XF)
Applications
1 Detection of battery charge/discharge current (for notebook computers, word processors etc)
2 Amplification of magnetic sensor, pressure sensor, strain gauge, other signals
3 Instrumentation amp
MITSUMI
Sensor Amplifier MM1089
Pin Assignment
1
+IN1
Rg1
-IN1
OUT1
Rs1
O.COM1
GND
2
3
4
5
6
7
8
9
18
V
CC
+IN2
Rg2
+
-
-IN2
Rs2
OUT2
O.COM2
+
-
O.COM2
17
16
15
14
13
12
11
10
A1
A2
Input range
switching 1
Input range
switching 2
Pin no.
Pin name
Function
1
Input range switching 1
AMP1 Input voltage range switching
INCHG1
Hi : 1.8V~V
CC
+0.3V LO : -0.3V~V
CC
-1.8V
2
IN1+
AMP1 +Input
3
Rg1+
AMP1 Resistance to set the Rg gain
4
Rg1-
AMP1 Resistance to set the Rg gain
5
IN1-
AMP1 -Input
6
Rs1
AMP1 Resistance to set the Rs gain
7
OUT1
AMP1 Resistance to set the Rs gain, output 1
8
O.COM1
AMP1 Common output
9
GND
Ground
10
O.COM2
AMP2 Common output
11
OUT2
AMP2 Resistance to set the Rs gain, output 2
12
Rs2
AMP2 Resistance to set the Rs gain
13
IN2-
AMP2 -Input
14
Rg2-
AMP2 Resistance to set the Rg gain
15
Rg2+
AMP2 Resistance to set the Rg gain
16
IN2+
AMP2 +Input
17
Input range switching 2
AMP2 Input voltage range switching
INCHG2
Hi : 1.8V~V
CC
+0.3V Lo : -0.3V~V
CC
-1.8V
18
V
CC
Power supply input
MITSUMI
Sensor Amplifier MM1089
Equivalent Circuit Diagram
Absolute Maximun Ratings
(Ta=25C)
Item
Symbol
Ratings
Units
Operating temperature
T
OPR
-20~+70 C
Storage temperature
T
STG
-40~+125
C
Power supply voltage
V
CC
-0.3~+25
V
Allowable loss
Pd
350
mW
Electrical Characteristics
(Except where noted otherwise, Ta=25C, V
CC
=15V, Rg=10k
, Rs=1000k
)
Item
Symbol
Measurement conditions
Min. Typ. Max. Units
Consumption current
I
CC
0.45
0.6
mA
Gain
G
V
G
V
=K Rs/Rg
See Fig. 1
Gain error
G
V
Error of above formula
-5
0
+5
%
Input bias current 1
I
B
1
When input range switching pin is high
50
250
nA
Input bias current 2
I
B
2
When input range switching pin is low
-100 -500
nA
Input offset current
I
IO
5
50
nA
Input offset voltage
V
IO
-2
0
+2
mV
O.COM pin setting
V
OC
Output takes O.COM pin
1.0
V
CC
-1.5
V
voltage range
voltage as reference
O.COM pin
I
OC
MM1089
-50
nA
input bias current
MM1131
-100
Output offset voltage
V
OO
V
OC
as reference (G
V
=40dB)
-0.25
0
+0.25
V
Output offset current
I
OO
V
OC
as reference (G
V
=40dB)
-0.25
0
+0.25
A
Common-mode input range 1
V
ICM
1
When input range switching pin is high
1.8
V
CC
+0.3
V
Common-mode input range 2
V
ICM
2
When input range switching pin is low
-0.3
V
CC
-1.8
V
Input voltage high level
V
HSW
2.4
V
for input range switching pin
Input voltage low level
V
LSW
0.8
V
for input range switching pin
Input current (Hi) for
I
HSW
V
INSW
=15V
-1
1
A
input range switching pin
Input current (Lo) for
I
LSW
V
INSW
=0V
-5
-0.5
A
input range switching pin
Output outflow current
I
SOURC
V
IN(+)
-V
IN(-)
=+1V, V
O
=V
CC
-1.5V
1.0
4.0
mA
O.COM=5V
Output inflow current
I
SINK
V
IN(+)
-V
IN(-)
=-1V, V
O
=0.3V
0.3
1.0
mA
O.COM=5V
Slew rate
SR
0.16
V/S
Common-mode signal rejection ratio
CMR
DC
80
100
dB
Power supply fluctuation
SVR
DC
80
100
dB
rejection ratio
Input equivalent noise voltage
VNI
R
IN
=1k
, BPF=20Hz~20kHz
6
V
MITSUMI
Sensor Amplifier MM1089
Characteristics
Common-mode input voltage range
Voltage gain vs frequency characteristic
0
2
4
6
8 10 12 14 16 18
40
30
20
10
SV.B
SV.A
SV.B
SV.A
Voltage gain G
V
[dB]
DC input voltage V
ICM
[V]
40
30
20
10
10
1
10
2
10
3
10
4
10
5
Rg=10k
Rg=33k
Rg=100k
Rg=1000k
Voltage gain G
V
[dB]
Frequency f [Hz]
Consumption voltage vs power supply voltage
Maximum output voltage vs Re
6
8 10 12 14 16 18 20 22 24
0.6
0.5
0.4
Consumption current
I
CC
[mA]
Power supply voltage V
CC
[V]
2
4
6
8
10
12
14
16
Frequency f [Hz]
10
2
10
3
10
4
10
5
Rs=500k
Rs=750k
Rs=1000k
Rs=200k
Rs=10k
Maximum output voltage
VOM
(Vop-p) [V]
Power supply fluctuation rejection ratio vs frequency
Common mode component rejection ratio
vs frequency
40
50
60
70
80
90
100
Frequency f [Hz]
10
1
10
2
10
3
10
4
10
5
Power supply fluctuation rejection
ratio SVR [dB]
40
50
60
70
80
90
100
10
1
10
2
10
3
10
4
10
5
Common mode component rejection
ratio CMR [
dB
]
Frequency f [Hz]
MITSUMI
Sensor Amplifier MM1089
Gain Settings
1. By mounting appropriate external Rs and Rg resistances, a subtractive amp can easily be configured with a
gain Gv=K R
S
/Rg (where K=1 typ.).
Here the precision of R
S
and Rg affects the gain, but has no inherent effect on CMR.
However, the practical range for the gain is Gv=3 to 100.
2. To determine R
S
and Rg, first R
S
is calculated from the maximum required output voltage; then the
equation for the gain Gv=K R
S
/Rg is used to compute Rg.
The voltage gain coefficient K varies with the value of Rg. For approximate values of K see Fig.1. The larger
the value of R
S
, the larger is the output offset voltage.
If R
S
is made small, an advantageous offset voltage is obtained, but if it is too small, an adequate maximum
output voltage is not obtained.
As a rough estimate, when the maximum output voltage is to be 10V
P-P
, Rs=1000k
; if it is to be 5V
P-P
,
then Rs=500k
.
Recommended values:
When Rs=1000 k
, Gv=100, Rg=9.1k
When Rs=1000 k
, Gv=50, Rg=18k
When Rs=500k
, Gv=50, Rg=9.1k
When Rs=500k
, Gv=10, Rg=47k
3. The output offset voltage ratings in the table of electrical characteristics are for Rg=10k
, Rs=1000k
.
When using other constants, use the following formula for the output offset:
Output offset=V
IO
G
V
+I
OO
R
S
4. The output voltage is essentially the voltage applied to the O.COM (OUTPUT COMMON) pin, output as the
reference level. In actuality, an offset is added to the reference potential and output.
Because the O.COM pin is independent of both amps 1 and 2, offset adjustment is easily accomplished by
shifting the O.COM pin voltage by the amount of the offset.
5. If the input range switching pin is set high, the input voltage range is covered from the V
CC
level; by
switching it to low, the range extends from GND level.
However, the offsets are different, so care must be taken in continuous switching.
6. The O.COM pin setting voltage range and common-mode input range should be set to voltages between
the minimum and maximum values.
10
0
10
1
10
2
10
3
0.84
0.86
0.88
0.90
0.92
0.94
0.96
0.98
1.00
MM1089
Voltage gain coefficient K
Fig. 1 Rg (k
)
[Voltage gain coefficient K vs. Rg]
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