Datasheet

UNISONIC TECHNOLOGIES CO., LTD
M7206
CMOS IC
3 1/2 LCD DISPLAY DRIVER, A/D
CONVERTERS

DESCRIPTION
The UTC M7206 is a 3 1/2 A/D converter IC with low power supply
and excellent performance, which also can greatly refrain form
interfering. The M7206 combines seven -phase decoder, display
driver, reference source, clock system and back light polarity driver, so
it can directly drive LCD. Compared with other products, the M7206
adds a new function that can detect on-off state and then alarm.
The M7206 covers high-precision, good compatibility and low-cost
in all. It can achieve auto-zero adjustment error less than 10uV, zero
drift within 1uV/°C, input current below 10pA and converter error
under 1 count.

FEATURES
* On-off state detecting and alarming
* Zero auto-adjustment, guaranteed zero reading with zero input.
* True polarity indication for precision null detection.
* Differential inputs and differential reference.
* Triplex LCD display.
* Convenient 9V battery operation
* CMOS differential inputs for high impedance and null attenuation
* Low noise and A/D converter,
* Low noise A/D converter, stable display.
* Inner clock circuit , can form astable multi-vibrator by connecting
passive electronic component.
* Optional exterior clock signal input
* Has triggered buttons that keep and low voltage alarm function that
power
* On-chip voltage reference, 60ppm/°C drift.

ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
M7206L-QL1-Y
M7206G-QL1-Y
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Copyright © 2013 Unisonic Technologies Co., Ltd
Package
Packing
LQFP-44
Tray
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M7206
CMOS IC
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PIN CONFIGURATIONS

PIN DESCRIPTION
PIN
NAME
TYPE
1
BZ
O
2
BZEN
I
3
4
TEST
OSC3
-
5
HOLD
O
OSC2
OSC1
V+
A1~G1
A2~G2
A3~G3
P
O
O
O
26
AB4
O
27
28
33
34
35
36
37
38
39
40
41
42
43
44
POL
BP
LOWB
VINT
BUFF
A/Z
IN LO
IN HI
COMMON
C-REFC-REF+
REF LO
REF HI
O
O
O
P
I
I
O
I
I
6
7
8
9~15
16~21、32
22~25, 29~31
PIN DESCRIPTION
Piezo buzzer output. Whenever BZEN is connected to V+ and
differential inputs are tied together, BZ will generate a 5KHz sound
output.
Buzzer control slave input. This pin is internally pulled-down to
TEST.See BZ
Digital GND. Pull high to V+ all LCD segments will be activated.
Crystal oscillator connection. (RC)
Hold control pin. When it receives a negative mud pulse, display hold;
Receive again then function disabled.
Crystal oscillator connection. (output)
Crystal oscillator connection. (input)
Positive supply voltage
LCD segment drive (unit)
LCD segment drive (decade)
LCD segment drive (hundred)
LCD segment drive (thousand). When the readout exceeds 1999, AB4
drive the segment of thousand to display ‘1’ for showing excess.
LCD segment drive. (minus ‘-‘)
LCD common drive.
LCD segment drive. (low battery)
Negative supply voltage. Connecting to battery negative terminal.
Integrator output.
Integration register connection
Auto-zero capacitor connection
Analog low input signal
Analog high input signal
Set the common-mode voltage for the system
Negative capacitor connection for on-chip A/D converter
Positive capacitor connection for on-chip A/D converter
Low differential reference input connection.
High differential reference input connection
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PIN FIGURE

PIN COORDINATES
PIN
Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
BZ
BZEN
TEST
OSC3
HOLD
OSC2
OSC1
V+
D1
C1
B1
A1
F1
G1
E1
D2
C2
B2
A2
F2
E2
D3
B3
Coordinate
X
Y
2135
325
2135
475
2135
625
2135
885
2135
1035
2135
1185
2135
1335
2135
1550
2135
1710
2135
1860
2135
2010
1970
2115
1820
2115
1670
2115
1520
2115
1370
2115
1220
2115
1070
2115
920
2115
770
2115
620
2115
470
2115
320
2115
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
PIN
Name
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
F3
E3
AB4
POL
BP
HLDO
BPG3
A3
C3
G2
LB
VINT
BUF
AZ
IN LO
IN HI
COM
CREFCREF+
RF LO
RF HI
Coordinate
X
Y
130
2115
95
1965
95
1815
95
1665
95
1515
95
1365
95
1165
95
1015
95
865
95
715
95
565
95
415
95
265
570
95
725
95
880
95
1030
95
1350
95
1510
95
1670
95
1820
95
1970
95
2120
95
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M7206
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CMOS IC
BLOCK DIAGRAM
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
CMOS IC
ABSOLUTE MAXIMUM RATING (unless otherwise specified)
PARAMETER
SYMBOL
RATINGS
UNIT
Power Supply Voltage(V+~V-)
VCC
12
V
Analog input voltage
VIANG
V+~VV
Reference Input Voltage
VIREF
V+~VV
Operating Temperature Range
TOPR
0 ~ 70
°C
Storage Temperature
TSTG
-65 ~ +150
°C
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.

ELECTRICAL CHARACTERISTICS
(VCC=9V, TA=25°C, unless otherwise specified)
PARAMETER
VCC Range
Supply Current(Does not conclude
COMMON current )
SYMBOL
VCC
ICC
TEST CONDITIONS
TYP
9
MAX
UNIT
V
0.6
1.2
mA
-000.0
±000.0
+000.0
999
999/
1000
1001
-1
± 0.2
+1
Counts
-1
6.6
± 0.2
1
6.9
+1
10
7.2
Counts
PA
V
2.80
3.00
3.20
V
VIN=0V
DC characteristics Zero Input
Reading
VIN=0V, full-scale=200mV
Ratio metric Reading
VIN=VREF, VREF=100mV
Linearity (MAX. deviation form best
straight line fit)
Roll-over Error
Input Leakage Current
Low battery flag
Analog Common Voltage
( with respect to V+)
full-scale=200.0mV or
full-scale=2.0V
-VIN=+VIN ~ 200mV
VIH=0V
V+ to V25kΩ Between Common
and Positive Supply
UNISONIC TECHNOLOGIES CO., LTD
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MIN
Digital
Reading
Digital
Reading
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CMOS IC
TYPICAL APPLICATIONS CIRCUITS
Figure 1
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CMOS IC
Detailed Description
Analog Section
The measurement cycle of analog section is divided into three phases. They are (1)auto-zero(A-Z),(2) signal
integrate(INT)and (3) de-integrate(DE).
Auto-Zero Phase
During auto-zero three things happen. First, input high and low are disconnected from the pins and internally
shorted to Analog COMMON. Second, the reference capacitor is charged to the reference voltage. Third, a feedback
loop is closed around the system to charge the auto-zero capacitor CAZ to compensate for offset voltages in the
buffer amplifier, integrator and comparator. Since the comparator is included in the loop, the A-Z accuracy is limited
only by the noise of the system. In any case, the offset referred to the input is less than 10uV.
Signal Integrate Phase
During signal integrate the auto-zero loops are opened, the internal short is removed, and the internal inputs high
and low are connected to the external pins. The converter then integrates the differential voltage between INHI and
INLO for a fixed time. This differential voltage can be within a wide common mode range: up to 1V from either supply.
On the other hand, if the input signal has no return with respect to the converter power supply, IN LO can be tied to
analog COMMON to establish the correct common mode voltage. At the end of this phase, the polarity of the
integrated signal is determined.
De-Integrate Phase
The final phase is de-integrated, or reference integrates. Input low is internally connected to analog COMMON and
input high is connected across the previously charged reference capacitor. Circuitry within the chip ensures that the
capacitor will be connected with the correct polarity to cause the integrator output to return to zero. The time required
for the output to return to zero is proportional to the input signal. Specifically the digital reading displayed is:
DISPLAY COUNT=1000(VIN/VREF)
Differential Input
The input can accept differential voltages anywhere within the common mode range of the input amplifier, or
specifically from 0.5V below the positive supply to 1V above the negative supply. In this range, the system has a
CMRR of 86dB typical. However, we must make sure that the integrator output does not saturate. A worst case
condition would be a large positive common mode voltage with a near full scale negative differential input voltage.
The negative input signal drives the integrator positive when most of its swing has been used up by the positive
common mod e voltage. For these critical applications the integrator output swing can be reduced to less than the
recommended 2V full scale swing with little loss of accuracy. The integrator output can swing to within 0.3V of either
supply without loss of linearity.
Differential Reference
The reference voltage can be generated anywhere within the power supply voltage of the converter. The main
source of common mode error is a roll-over voltage caused by the reference capacitor losing or gaining charge to
stray capacity on its nodes. If there is a large common mode voltage, the reference capacitor can gain change when
called up to de-integrate a positive signal but lose charge when called up to de-integrate a negative input signal. This
difference in reference for positive or negative input voltage will give a roll-over error. However, by selecting the
reference capacitor such that it is large enough in comparison to the stray capacitance, this error can be held to less
than 0.5 count worst case.
Analog Common
The COM pin is used to set the common-mod voltage for the system where the input signals are floating with
respect to the power supply. It sets a voltage that is approximately 2.8V lower than the positive supply. In most of the
applications, IN LO, RF LO and COM pins are tied to the same point, so that the common mode voltage can be
removed from the reference system and the converter.
Within the IC, analog COMMON is tied to an N-Channel FET that can sink approximately 30mA of current to hold
the voltage 2.8V below the positive supply (when a load is trying to pull the common voltage toward the positive
supply). However, there is only 10μA of source current, so COM voltage is easily tied to a more negative voltage with
respect to the positive supply.
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CMOS IC
Detailed Description(Cont.)
TEST
The TEST pin serves two functions. Within IC it is coupled to the internally generated digital supply through an
NMOS. Thus it can be used as the negative supply for externally generated segment drivers such as decimal points
or any other presentation the user may want to include on the LCD display. The second function is a “lamp test”.
When TEST is pulled high(to V+)all segment will be turned on and output should be “1888”.
Component Value Selection
Integrating Resistor
Both the buffer amplifier and the integrator have an output stage with 100μA of quiescent current. They can supply
4μA of drive current with negligible nonlinearity. The integrating resistor should be large enough to remain in this
very linear region over the input voltage range, but small enough that undue leakage requirements are not placed on
the PC board. For 2V full scale, 470kΩ is near optimum and similarly a 47kΩ for a 200mV scale.
Integrating Capacitor
The integrating capacitor should give the maximum voltage swing that ensures tolerance buildup will not saturate
the integrator swing (approximately. 0.3V from either supply). When the analog COMMON is used as a reference, a
nominal +2V full-scale integrator swing is fine. For three readings /second (48 kHz clock) nominal values for ClNT
are 0.22μF and 0.10μF, respectively. Of course, if different oscillator frequencies are used, these values should be
changed in inverse proportion to maintain the same output swing.
An additional requirement of the integrating capacitor is that it must have a low dielectric absorption to prevent
roll-over errors. While other types of capacitors are adequate for this application, polypropylene capacitors give the
best choice.
Auto-Zero Capacitor
The size of the auto-zero capacitor has some influence on the noise of the system. For 200mV full scale where
noise is very important, a 0.47μF capacitor is recommended. On the 2V scale, a 0.047μF capacitor increases the
speed of recovery from overload and is adequate for noise on this scale.
Oscillator Components
For all ranges of frequency a 100kΩ resistor is recommended and the capacitor is selected from the equation:
f  0.45 / RC For 48kHz clock(3 Reading/sec),
C=100pF.
Reference Capacitor
A 0.1μF capacitor gives good results in most applications. However, where a large common mode voltage exists
and a 200mV scale is used, a larger value is required to prevent roll-over error. Generally 1μF will hold the roll-over
error to 0.5 count in this instance.
Reference Voltage
The analog input required to generate full scale output (2000 counts) is: VIN  2VREF . Thus, for the 200mV and 2V
scale, VREF should equal 100mV and 1V, respectively. However, in some applications the full-scale input voltage may
be other than 200mV or 2V, but 600mV. For example, the reference voltage should be set to 300mV and the input
signal can be used directly without being divided.
The differential reference can be used during the measurement of resistor by the ratio metric method and when a
digital reading of zero is desired for VIN≠0. A compensating offset voltage can be applied between COM and IN LO
and the voltage of being measured is connected between COM and IN HI.
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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