Microchip Technology TC7126CLW, TC7126CKW, TC7126ARIPL, TC7126ARCPL, TC7126AIPL Datasheet
...
TC7126/A
3-1/2 Digit Analog-to-Digital Converters
Features
• Internal Reference with LowTemperature Drift
- TC7126: 80ppm/°C Typical
- TC7126A: 35ppm/°C Typical
• Zero Reading with Zero Input
• Low Noise: 15µV
• High Resolution: 0.05%
• Low Input Leakage Current: 1pA Typ., 10pA Max.
• PrecisionNull Detectors with True Polarity at Zero
• High-ImpedanceDifferential Input
• Convenient9V Battery Operation with Low Power
Dissipation: 500µWTyp.,900µWMax.
P-P
Applications
• Thermometry
• Bridge Readouts: StrainGauges, Load Cells,
Null Detectors
• Digital Meters and Panel Meters:
- Voltage/Current/Ohms/Power, pH
• Digital Scales, Process Monitors
Device Selection Table
Package
Code
CPL 40-Pin PDIP 0°Cto+70°C
IPL 40-Pin PDIP (TC7126Only) -25°Cto+85°C
CKW 44-Pin PQFP 0°Cto+70°C
CLW 44-Pin PLCC 0°Cto+70°C
Package
Temperature
Range
General Description
The TC7126A is a 3-1/2 digit CMOS analog-to-digital
converter (ADC) containing all the active components
necessary to construct a 0.05% resolution measurement system. Seven-segment decoders, digit and
polarity drivers, voltage reference, and clock circuit are
integrated on-chip. The TC7126A directly drives a liquid crystal display (LCD), and includes a backplane
driver.
A low cost, high resolution indicating meter requires
only a display, four resistors, and four capacitors. The
TC7126A's extremely low power drain and 9V battery
operation make it ideal for portable applications.
The TC7126A reduces linearity error to less than 1
count. Rollover error (the difference in r eadings for
equal magnitude, but opposite polarity input signals) i s
below ±1 count. High-impedance differential inputs
offer 1pA leakage current and a 10
ance. The 15µV
solid" reading, and the auto-zero cycle ensures a zero
display reading with a 0V input.
The TC7126A features a precision, low drift internal
voltage reference and is functionally i dentical to the
TC7126. A l ow drift external reference is not normally
required with the TC7126A.
noise performance ensures a "rock
P-P
12
Ω input imped-
2002 Microchip TechnologyInc. DS21458B-page 1
TC7126/A
Package Type
1
A
B1C1D1V+
6543 1442
F
7
1
G
8
1
E
9
1
D
10
2
C
11
2
12
NC
B
13
2
A
2
F
2
E
2
D
3
18 19 20 21 23 24
3
3
B
F
V+
D
1
C
1
B
1
A
1's
1
F
1
G
1
E
1
D
2
C
2
B
A
F
E
D
B
F
E
AB
POL
2
2
2
2
3
3
3
3
4
10's
100's
1000's
(Minus Sign)
44-Pin PLCC
OSC1
OSC242OSC341TEST
NC
43
TC7126CLW
TC7126ACLW
NC
BP
25 26 27 28
G
22
4
3
E
AB
POL
40-Pin PDIP (Normal)
1
Normal Pin
2
Configuration
3
4
5
6
7
TC7126CPL
8
TC7126ACPL
TC7126IPL
9
TC7126AIPL
10
11
12
13
14
15
16
17
18
19
20
40
3A3C3G2
40
OSC1
39
OSC2
38
OSC3
37
TEST
36
+
V
REF
35
-
V
REF
34
+
C
REF
C
-
33
REF
ANALOG
32
COMMON
31
V
+
IN
30
-
V
IN
C
29
AZ
28
V
BUFF
27
V
INT
26
V-
25
G
2
24
C
3
23
A
3
22
G
3
21
BP
(Backplane)
+
REF
V
100's
V
39
C
38
C
37
ANALOG
36
COMMON
V
35
34
NC
V
33
3214
C
3115
V
3016
V
2917
V-
REF
REF
REF
+
IN
-
IN
AZ
BUFF
INT
44-Pin PQFP
-
+
+
+
REF
REF
REF
REF
V
V
C
C
44 43 42 41 39 3840
NC
NC
TEST
OSC3
NC
OSC2
OSC1
V+
D
C
B
1
2
3
4
5
6
7
8
9
1
10
1
11
1
12 13 14 15 17 18
1
1G1E1
F
A
TC7126CKW
TC7126ACKW
16
-
+
-
-
IN
ANALOG
IN
COMMON
V
V
2
2B2A2F2E2
D
C
AZ
BUFF
INT
C
V
37
V
36
35
19 20 21 22
V-
34
33
NC
32
G
2
C
31
3
A
30
3
G
29
3
BP
28
POL
27
AB
26
4
E
25
3
F
24
3
B
23
3
3
D
44-Pin PDIP (Reverse)
OSC1
OSC2
OSC3
TEST
V
REF
V
REF
C
REF
C
REF
ANALOG
COMMON
V
IN
V
IN
C
AZ
V
BUFF
V
INT
V-
G
C
100's
A
G
BP
(Backplane)
1
2
3
4
+
5
-
6
+
7
TC7126RCPL
-
8
TC7126ARCPL
9
TC7126ARIPL
+
10
-
11
12
13
14
15
16
2
17
3
18
3
19
3
20
Reverse Pin
Configuration
TC7126RIPL
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
V+
D
1
C
1
B
1
A
1's
1
F
1
G
1
E
1
D
2
C
2
B
2
10's
A
2
F
2
E
2
D
3
B
3
100's
F
3
E
3
AB
1000's
4
POL
(Minus Sign)
DS21458B-page 2
NC = No Internal Connection
2002 Microchip TechnologyInc.
Typical Application
TC7126/A
+
Analog
Input
–
1MΩ
0.01µF
180kΩ
0.15µF
0.1µF
2–19
POL
BP
V+
REF
REF
V-
TC7126A
Segment
Drive
20
21
1
36
+
35
26
0.33
µF
34
+
REF
31
+
V
IN
30
-
V
IN
ANALOG
32
COMMON
28
V
BUFF
29
C
AZ
27
V
INT
39 38 40
R
OSC
560kΩ
33
C
REF
C
OSC
50pF
-C
22–25
V
V
OSC1OSC3OSC2
Note: Pin numbers refer to 40-pin DIP.
TC7126
Minus Sign
240kΩ
10kΩ
1 Conversion/Sec
To Analog Common (Pin 32)
LCD
Backplane
+
9V
2002 Microchip TechnologyInc. DS21458B-page 3
TC7126/A
Functional Block Diagram
V+
0.5mA
LCD
Output
Segment
2mA
BP
6.2V
Control Logic
4
OSC
F
Clock
TEST
V+
1
V
INT
÷ 200
Decode
7-Segment
Decode
7-Segment
Decode
7-Segment
27333634
Data Latch
Section
To Digital
+
Tens Units
Hundreds
Thousands
Comparator Output
To Switch Drivers From
–
21
LCD Segment Drivers
INT
C
V-
26
500Ω
= 1V
TH
V
Internal Digital Ground
OSC3OSC1
39
OSC
OSC2
R
OSC
C
Typical Segment Output
AZ
C
INT
R
TC7126A
REF
C
–
–
ZI &
ZI & AZ
10
+
+
AZ
µA
Integrator
29
1
V+
28
BUFF
V
-
REF
C
35
REF
+V
REF
V
+
REF
C
AZ
ZI
31
Comparator
Low
DE
(+)
(–)
DE
INT
+
IN
V
REF
Temp Co
V
–
+
V+ – 2.8V
DE (–)
DE (+)
32
Analog
AZ & DE (±)
-
IN
V
Common
26
40 38
V-
INT
DS21458B-page 4
2002 Microchip TechnologyInc.
TC7126/A
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings*
Supply Voltage (V+ to V-).......................................15V
Analog Input Voltage(either Input) (Note 1)... V+ to V-
*Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to the device. These
are stress ratings only and functional operation of the device
at these or any other conditions above those indicated in the
operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affectdevice reliability.
Reference Input Voltage (either Input)............ V+ to V-
Clock Input ................................................... Test to V+
Package Power Dissipation (T
≤ 70°C) (Note 2):
A
44-Pin PQFP...............................................1.00W
40-Pin PLCC...............................................1.23W
44-Pin PDIP ................................................1.23W
Operating Temperature Range:
C (Commercial) Devices.................. 0°C to +70°C
I (Industrial) Devices....................-25°Cto +85°C
StorageTemperature Range..............-65°C to +150°C
TC7126/A ELECTRICAL SPECIFICATIONS
Electrical Characteristics: VS=+9V,f
Symbol Parameter Min Typ Max Unit Test Conditions
Input
Z
IR
Z
RD
NL LinearityError -1 ±0.2 1 Count FullScale= 200mV or 2V
e
N
I
L
CMRR Common Mode Rejection Ra tio — 50 — µV/V V
Analog Common
V
CTC
V
C
Note 1: Input voltages may exceed the supply voltages, provided the input current is limited to ±100µA.
Zero InputReading -000.0 ±000.0 +000.0 Digital
Zero Reading Dri ft — 0.2 1 µV/°C VIN=0V,0°C≤ TA≤ +70°C
Ratiometric Reading 999 999/1000 1000 Digital
Rollover Error -1 ±0.2 1 Count V
Noise — 15 — µV
Input Leakage Current — 1 10 pA VIN=0V
Scale Factor Temperature
Coefficient
Analog Common Temperature
Coefficient
Analog Common Voltage 2.7 3.05 3.35 V 250kΩ BetweenCommonandV+
2: Dissipationrating assumes device is mounted with all leads solderedto printedcircuit board.
3: Refer to “Differential Input” discussion.
4: Backplane drive is in phasewith segment drive for “OFF” segment,180°out of phase for “ON” segment. Frequency is
20 times conversion rate. Average DC component is less than 50mV.
5: See “Typical Application”.
6: During Auto-Zero phase, current is 10-20µA higher. A 48kHz ocillatorincreases currentby 8µA (Typical). Common
current is not included.
– 16kHz, and TA= +25°C, unless otherwise noted.
CLK
—1 5ppm/°CV
— — — — 250kΩ Between Commonand V+
——— —0°C≤ T
— 80 — ppm/°C TC7126
— 35 75 ppm/°C TC7126A
— 35 100 ppm/°C -25°C ≤ T
Reading
Reading
P-P
VIN=0V
Full Scale = 200mV
V
IN=VREF,VREF
Max DeviationF rom B est Fit
StraightLine
-=VIN+ ≈ 200mV
IN
VIN= 0V,FullScale= 200mV
=±1V,VIN=0V
CM
Full Scale = 200mV
=199mV,0°C≤ TA≤ +70°C
IN
Ext. Ref. Temp Coeff. = 0ppm/°C
≤ +70°C ("C" Devices)
A
(TC7126A)
=100mV
≤ +85°C ("I" Device)
A
2002 Microchip TechnologyInc. DS21458B-page 5
TC7126/A
TC7126/A ELECTRICAL SPECIFICATIONS (CONTINUED)
Electrical Characteristics: VS=+9V,f
Symbol Parameter Min Typ Max Unit Test Conditions
LCD Drive
V
LCD Segment DriveVoltage 4 5 6 V
SD
LCD Backplane Drive Voltage 4 5 6 V
V
BD
Power Supply
I
Power SupplyCurrent — 55 100 µAVIN= 0V, V+ to V- = 9V (Note 6)
S
Note 1: Input voltages may exceed the supply voltages, provided the input current is limited to ±100µA.
2: Dissipationrating assumes device is mounted with all leads solderedto printedcircuit board.
3: Refer to “Differential Input” discussion.
4: Backplane drive is in phasewith segment drive for “OFF” segment,180°out of phase for “ON” segment. Frequency is
20 times conversion rate. Average DC component is less than 50mV.
5: See “Typical Application”.
6: During Auto-Zero phase, current is 10-20µA higher. A 48kHz ocillatorincreases currentby 8µA (Typical). Common
current is not included.
– 16kHz, and TA= +25°C, unless otherwise noted.
CLK
P-P
P-P
V+ to V- = 9V
V+ to V- = 9V
DS21458B-page 6
2002 Microchip TechnologyInc.
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
Pin Number
(40-Pin PDIP)
Normal
1 (40) V+ Positive supply voltage.
2(39)D
3(38)C
4(37)B
5(36)A
6(35)F
7(34)G
8(33)E
9(32)D
10 (31) C
11 (30) B
12 (29) A
13 (28) F
14 (27) E
15 (26) D
16 (25) B
17 (24) F
18 (23) E
19 (22) AB
20 (21) POL Activates the negativepolarity display.
21 (20) BP LCD Backplane drive output(TC7106A). Digital Ground (TC7107A).
22 (19) G
23 (18) A
24 (17) C
25 (16) G
26 (15) V- Negative power supply voltage.
27 (14) V
28 (13) V
29 (12) C
30 (11) V
31 (10) V
32 (9) ANALOG
33 (8) C
(Reversed) Symbol Description
Activates the D sectionof the unitsdisplay.
1
Activates the C sectionof the unitsdisplay.
1
Activates the B section of the units display.
1
Activates the A section of the units display.
1
Activates the F section of the units display.
1
Activates the G section of the unitsdisplay.
1
Activates the E section of the units display.
1
Activates the D section of the tensdisplay.
2
Activates the C section of the tensdisplay.
2
Activates the B sectionof the tensdisplay.
2
Activates the A sectionof the tensdisplay.
2
Activates the F section of the tens display.
2
Activates the E sectionof the tensdisplay.
2
Activates the D section of the hundreds display.
3
Activates the B section of the hundreds display.
3
Activates the F section of the hundreds display.
3
Activates the E section of the hundreds display.
3
Activates both halves of the 1 in the thousands display.
4
Activates the G section of the hundreds display.
3
Activates the A section of the hundreds display.
3
Activates the C section of the hundreds display.
3
Activates the G section of the tensdisplay.
2
The integrating capacitor should be selected to give the maximum voltage swing that
INT
ensures component tolerance buildup will not allow the integrator output to saturate.
When analog common is used as a reference and the conversion rate is 3 readings
per second, a 0.047µF capacitor may be used. The capacitor must have a low
dielectric constant to preventrollover errors.See Section 6.3, IntegratingCapacitor
for additional details.
BUFF
Integration resistor connection. Use a 180kΩ resistor for a 200mV full-scale range
anda1.8MΩ resistor for a 2V full scalerange.
The size of the auto-zero capacitor influences system noise. Use a 0.33µF capacitor
AZ
for 200mV full scale,and a 0.033µF capacitorfor2V full scale.See Section6.1,
Auto-Zero Capacitorforadditionaldetails.
- The analog LOW input is connected to this pin.
IN
+ The analog HIGH input signal is connected to this pin.
IN
This pin is primarily used to set the Analog Common mode voltage for battery opera-
COMMON
tion, or in systems where the input signalis referenced to the powersupply.It also
actsas a reference voltage source. See Section 7.3, AnalogCommon for additional
details.
- See Pin 34.
REF
TC7126/A
2002 Microchip TechnologyInc. DS21458B-page 7
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