TC7129
4-1/2 Digit Analog-to-Digital Converters with
On-Chip LCD Drivers
Features
•
•
•
•
•
•
•
•
•
Count Resolution: ±19,999
Resolution on 200 mV Scale: 10µV
True Differential Input and Reference
Low Power Consumption: 500µA at 9V
Direct LCD Driver for 4-1/2 Digits, Decimal Points,
Low Battery Indicator, and Continuity Indicator
Overrange and Underrange Outputs
Range Select Input: 10:1
High Common Mode Rejection Ratio: 110 dB
External Phase Compensation Not Required
General Description
The TC7129 is a 4-1/2 digit Analog-to-Digital Converter
(ADC) that directly drives a multiplexed Liquid Crystal
Display (LCD). Fabricated in high-performance, low-
power CMOS, the TC7129 ADC is designed specifi-
cally for high-resolution, battery-powered digital multi-
meter applications. The traditional dual-slope method
of A/D conversion has been enhanced with a succes-
sive integration technique to produce readings accu-
rate to better than 0.005% of full-scale and resolution
down to 10 µV per count.
The TC7129 includes features important to multimeter
applications. It detects and indicates low battery condi-
tion. A continuity output drives an annunciator on the
display and can be used with an external driver to sound
an audible alarm. Overrange and underrange outputs,
along with a range-change input, provide the ability to
create auto-ranging instruments. For snapshot read-
ings, the TC7129 includes a latch-and-hold input to
freeze the present reading. This combination of features
makes the TC7129 the ideal choice for full-featured
multimeter and digital measurement applications.
Applications
• Full-Featured Multimeters
• Digital Measurement Devices
Device Selection Table
Package
Code
TC7129CPL
TC7129CKW
TC7129CLW
Pin
Layout
Normal
Formed
–
Package
40-Pin PDIP
44-Pin PQFP
44-Pin PLCC
Temperature
Range
0°C to +70°C
0°C to +70°C
0°C to +70°C
Typical Application
Low Battery
Continuity
V+
5 pF
20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
TC7129
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
120 kHz
330 kΩ
*
0.1 µF
1 µF
150 kΩ
+
+
0.1
µF
10 pF
20
kΩ
0.1 µF
V+
10 kΩ
9V
–
100 kΩ
+
*Note:
RC network between pins 26 and 28 is not required.
V
IN
2004 Microchip Technology Inc.
DS21459C-page 1
TC7129
Package Types
40-Pin PDIP
OSC1
OSC3
ANNUNICATOR
B
1
, C
1
, CONT
A
1
, G
1
, D
1
F
1
, E
1
, DP
1
B
2
, C
2
, LO BATT
A
2
, G
2
, D
2
F
2
, E
2
, DP
2
1
2
3
4
5
6
7
8
9
40 OSC2
39
DP
1
38 DP
2
37 RANGE
36 DGND
35 REF LO
34 REF HI
33 IN HI
32
IN LO
BUFF
B
3
, C
3
, MINUS 10
Display
Output
Lines
A
3
, G
3
, D
3
11
F
3
, E
3
, DP
3
B
4
, C
4
, BC
5
A
4
, G
4
, D
4
F
4
, E
4
, DP
4
BP
3
BP
2
BP
1
V
DISP
DP
4
/OR
12
13
14
15
16
17
18
19
20
TC7129CPL
31
30 C
REF
-
29 C
REF
+
28 COMMON
27 CONTINUITY
26 INT OUT
25 INT IN
24 V+
23 V-
22 LATCH/HOLD
21 DP
3
/UR
ANNUNCIATOR
B
1
, C
1
, CONT
A
1
, G
1
, D
1
B1, C1, CONT
44-Pin QFP
A1, G1, D1
RANGE
DGND
ANNUNCIATOR
44-Pin PLCC
RANGE
DGND
39 REF LO
38 REF HI
37 IN HI
36 IN LO
35 BUFF
34 NC
33 C
REF
-
32 C
REF
+
31 COMMON
30 CONTINUITY
29 INT OUT
INT IN
OSC3
OSC1
OSC2
OSC3
OSC1
OSC2
DP
1
DP
1
DP
2
NC
44 43 42 41 40 39 38 37 36 35 34
F
1
, E
1
, DP
1
1
B
2
, C
2
, BATT 2
A
2
, G
2
, D
2
3
F
2
, E
2
, DP
2
4
B
3
, C
3
, MINUS 5
NC 6
A
3
, G
3
, D
3
7
F
3
, E
3
, DP
3
8
B
4
, C
4
, BC
5
9
A
4
, G
4
, D
4
10
F
4
, E
4
, DP
4
11
12 13 14 15 16 17 18 19 20 21 22
DP
4
/OR
DP
3
/UR
LATCH/HOLD
V
DISP
INT IN
NC
BP
3
BP
2
BP
1
V+
V-
33 REF LO
32 REF HI
31 IN HI
30 IN LO
29 BUFF
F
1
, E
1
, DP
1
7
B
2
, C
2
, BATT
A
2
, G
2
, D
2
8
9
6
5
4
3
2
1
44 43 42 41 40
F
2
, E
2
, DP
2
10
B
3
, C
3
, MINUS 11
NC 12
A
3
, G
3
, D
3
13
F
3
, E
3
, DP
3
14
B
4
, C
4
, BC
5
15
A
4
, G
4
, D
4
16
F
4
, E
4
, DP
4
17
18 19 20 21 22 23 24 25 26 27 28
DP
4
/OR
NC
DP
3
/UR
BP
1
BP
3
BP
2
V
DISP
LATCH/HOLD
V+
V-
TC7129CKW
28 NC
27 C
REF
-
26 C
REF
+
25 COMMON
24 CONTINUITY
23 INT OUT
TC7129CLW
DS21459C-page 2
2004 Microchip Technology Inc.
DP
2
NC
TC7129
1.0
ELECTRICAL
CHARACTERISTICS
*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 affect device reliability.
Absolute Maximum Ratings*
Supply Voltage (V+ to V-)....................................... 15V
Reference Voltage (REF HI or REF LO) ........ V+ to V–
Input Voltage (IN HI or IN LO)
(Note 1)..........
V+ to V–
V
DISP
.......................................... V+ to (DGND – 0.3V)
Digital Input (Pins 1, 2, 19, 20,
21, 22, 27, 37, 39, 40) .......................... DGND to V+
Analog Input (Pins 25, 29, 30) ....................... V+ to V–
Package Power Dissipation (T
A
≤
70°C)
Plastic DIP ..................................................... 1.23W
PLCC ............................................................. 1.23W
Plastic QFP .................................................... 1.00W
Operating Temperature Range ............... 0°C to +70°C
Storage Temperature Range.............. -65°C to +150°C
TC7129 ELECTRICAL SPECIFICATIONS
Electrical Characteristics:
V+ to V– = 9V, V
REF
= 1V, T
A
= +25°C, f
CLK
= 120 kHz, unless otherwise indicated.
Pin numbers refer to 40-pin DIP.
Symbol
Input
Zero Input Reading
Zero Reading Drift
Ratiometric Reading
Range Change Accuracy
RE
NL
CMRR
CMVR
Rollover Error
Linearity Error
Common Mode Rejection Ratio
Common Mode Voltage Range
–0000
—
9996
0.9999
—
—
—
—
—
e
N
I
IN
Noise (Peak-to-Peak Value not
Exceeded 95% of Time)
Input Leakage Current
Scale Factor Temperature
Coefficient
Note 1:
—
—
—
0000
±0.5
—
1.0000
1
1
110
(V-) +
1.5
(V+) – 1
14
1
2
+0000
—
10000
1.0001
2
—
—
—
—
—
10
7
Counts V
IN
= 0V, 200 mV scale
µV/°C
V
IN
= 0V, 0°C < T
A
< +70°C
Counts V
IN
= V
REF
= 1000 mV,
Range = 2V
Ratio
V
IN
= 1V on High Range,
V
IN
= 0.1V on Low Range
Parameter
Min
Typ
Max
Unit
Test Conditions
Counts V
IN
– = V
IN
+ = 199 mV
Counts 200mV Scale
dB
V
V
µV
P-P
pA
V
CM
= 1V, V
IN
= 0V,
200 mV scale
V
IN
= 0V
200 mV scale
V
IN
= 0V
200 mV scale
V
IN
= 0V, pins 32, 33
ppm/°C V
IN
= 199 mV,
0°C < T
A
< +70°C
External V
REF
= 0 ppm/°C
Input voltages may exceed supply voltages, provided input current is limited to ±400 µA. Currents above
this value may result in invalid display readings, but will not destroy the device if limited to ±1 mA.
Dissipation ratings assume device is mounted with all leads soldered to printed circuit board.
2004 Microchip Technology Inc.
DS21459C-page 3
TC7129
TC7129 ELECTRICAL SPECIFICATIONS (CONTINUED)
Electrical Characteristics:
V+ to V– = 9V, V
REF
= 1V, T
A
= +25°C, f
CLK
= 120 kHz, unless otherwise indicated.
Pin numbers refer to 40-pin DIP.
Symbol
Power
V
COM
Common Voltage
Common Sink Current
Common Source Current
DGND
Digital Ground Voltage
Sink Current
Supply Voltage Range
I
S
f
CLK
Supply Current Excluding
Common Current
Clock Frequency
V
DISP
Resistance
Low Battery Flag Activation
Voltage
Digital
Continuity Comparator Threshold
Voltages
Pull-down Current
“Weak Output” Current
Sink/Source
Pin 22 Source Current
Pin 22 Sink Current
Note 1:
100
—
—
—
—
—
—
200
200
2
3/3
3/9
40
3
—
400
10
—
—
—
—
mV
mV
µA
µA
µA
µA
µA
V
OUT
pin 27 = High
V
OUT
pin 27 = Low
Pins 37, 38, 39
Pins 20, 21 sink/source
Pin 27 sink/source
2.8
—
—
4.5
—
6
—
—
—
6.3
3.2
0.6
10
5.3
1.2
9
0.8
120
50
7.2
3.5
—
—
5.8
—
12
1.3
360
—
7.7
V
mA
µA
V
mA
V
mA
kHz
kΩ
V
V
DISP
to V+
V+ to V–
V+ to pin 28
∆Common
= +0.1V
∆Common
= -0.1V
V+ to pin 36, V+ to V– = 9V
∆DGND
= +0.5V
V+ to V–
V+ to V– = 9V
Parameter
Min
Typ
Max
Unit
Test Conditions
Input voltages may exceed supply voltages, provided input current is limited to ±400 µA. Currents above
this value may result in invalid display readings, but will not destroy the device if limited to ±1 mA.
Dissipation ratings assume device is mounted with all leads soldered to printed circuit board.
DS21459C-page 4
2004 Microchip Technology Inc.
TC7129
2.0
PIN DESCRIPTIONS
PIN FUNCTION TABLE
Symbol
OSC1
OSC3
ANNUNCIATOR
B
1
, C
1
, CONT
A
1
, G
1
, D
1
F
1
, E
1
, DP
1
B
2
, C
2
,
LO BATT
A
2
, G
2
, D
2
F
2
, E
2
, DP
2
B
3
, C
3
, MINUS
A
3
, G
3
, D
3
F
3
, E
3
, DP
3
B
4
, C
4
, BC
5
A
4
, D
4
, G
4
F
4
, E
4
, DP
4
BP
3
BP
2
BP
1
V
DISP
DP
4
/OR
DP
3
/UR
LATCH/HOLD
Input to first clock inverter.
Output of second clock inverter.
Backplane square wave output for driving annunciators.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Output to display segments.
Backplane #3 output to display.
Backplane #2 output to display.
Backplane #1 output to display.
Negative rail for display drivers.
Input:
When high, turns on most significant decimal point.
Output:
Pulled high when result count exceeds ±19,999.
Input:
Second-most significant decimal point on when high.
Output:
Pulled high when result count is less than ±1000.
Input:
When floating, ADC operates in Free Run mode. When
pulled high, the last displayed reading is held. When pulled low,
the result counter contents are shown incrementing during the
de-integrate phase of cycle.
Output:
Negative going edge occurs when the data latches are
updated. Can be used for converter status signal.
Negative power supply terminal.
Positive power supply terminal and positive rail for display
drivers.
Input to integrator amplifier.
Output of integrator amplifier.
Input:
When low, continuity flag on the display is off. When high,
continuity flag is on.
Output:
High when voltage between inputs is less than +200 mV.
Low when voltage between inputs is more than +200 mV.
Sets common mode voltage of 3.2V below V+ for DE, 10X, etc.
Can be used as pre-regulator for external reference.
Positive side of external reference capacitor.
Negative side of external reference capacitor.
Output of buffer amplifier.
Negative input voltage terminal.
Positive input voltage terminal.
Positive reference voltage.
Negative reference voltage
Function
Descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
Pin No.
Pin No.
Pin No.
40-Pin PDIP 44-Pin PQFP 44-Pin PLCC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
40
41
42
43
44
1
2
3
4
5
7
8
9
10
11
12
13
14
15
16
18
19
2
3
4
5
6
7
8
9
10
11
13
14
15
16
17
18
19
20
21
22
24
25
23
24
25
26
27
20
21
22
23
24
26
27
28
29
30
V–
V+
INT IN
INT OUT
CONTINUITY
28
29
30
31
32
33
34
35
25
26
27
29
30
31
32
33
31
32
33
35
36
37
38
39
COMMON
C
REF
+
C
REF
–
BUFFER
IN LO
IN HI
REF HI
REF LO
2004 Microchip Technology Inc.
DS21459C-page 5
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