TelCom Semiconductor Inc TC7129CPL, TC7129CLW, TC7129CKW Datasheet

4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER
WITH ON-CHIP LCD DRIVERS

1

TC7129

2

FEATURES

■ Count Resolution.........................................±19,999

■ Resolution on 200 mV Scale.......................... 10 µV

■ True Differential Input and Reference

■ Low Power Consumption ...................500 µA 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

ORDERING INFORMATION

Pin Temperature

Part No. Layout Package Range

TC7129CKW Formed 44-Pin PQFP 0°C to +70°C
TC7129CLW — 44-Pin PLCC 0°C to +70°C
TC7129CPL Normal 40-Pin PDIP 0°C to +70°C

TYPICAL OPERATING CIRCUIT

LOW BATTERY CONTINUITY

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 specifically for high­resolution, battery-powered digital multimeter applications.
The traditional dual-slope method of A/D conversion has
been enhanced with a successive integration technique to
produce readings accurate 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 condition.
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 and a range­change input provide the ability to create auto-ranging
instruments. For snapshot readings, 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.

+

V

3

4

5

20

+

9V

NOTE:

*

TELCOM SEMICONDUCTOR, INC.

9

1011

12

13141516171819

TC7129

29

27262524232221

28

*

0.1 µF
1 µF

150 kΩ

10 kΩ

RC network between pins 26 and 28 is not required.

8

323130

33

0.1

+

µF

100 kΩ

–

V

IN

567

3534

36

20
kΩ

+

3837

TC04

5 pF

1234

6

120 kHz

39

40

330 kΩ

7

0.1 µF

V

10 pF

+

8

TC7129-5 10/18/96

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TC7129

4-1/2 DIGIT ANALOG-TO-DIGITAL

CONVERTER WITH ON-CHIP LCD DRIVERS

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

................................................V+ to (DGND – 0.3V)

DISP

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 (TA ≤ 70°C)

Plastic DIP ........................................................1.23W

PLCC ................................................................1.23W

Plastic QFP.......................................................1.00W

Operating Temperature Range .................... 0°C to +70°C

ELECTRICAL CHARACTERISTICS: V

+

to V– = 9V, V

Storage Temperature Range ................– 65°C to +150°C

Lead Temperature (Soldering, 10 sec) .................+300°C

–

Notes: 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.

+
–

*Static-sensitive device. Unused devices must be stored in conductive
material. Protect devices from static discharge and static fields. 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 operational sections of the specifications is not implied.
Exposure to Absolute Maximum Rating Conditions for extended periods
may affect device reliability.

= 1V, TA = +25°C, f

REF

= 120 kHz, unless otherwise

CLK

indicated. Pin numbers refer to 40-pin DIP.

Symbol Parameter Test Conditions Min Typ Max Unit

Input

Zero Input Reading VIN = 0V, 200 mV Scale – 0000 0000 +0000 Counts
Zero Reading Drift VIN = 0V, 0°C < TA < +70°C—±0.5 — µV/°C
Ratiometric Reading VIN = V
Range Change Accuracy V

= 0.1V on Low Range 0.9999 1.0000 1.0001 Ratio

IN

4VIN = 1V on High Range
RE Roll-Over Error –VIN = +VIN = 199 mV — 1 2 Counts
NL Linearity Error 200 mV Scale — 1 — Counts
CMRR Common-Mode Rejection Ratio VCM = 1V, VIN = 0V, 200 mV Scale — 110 — dB
CMVR Common-Mode Voltage Range V

= 0V — (V–) +1.5 — V

IN

200 mV Scale — (V+) –1 — V
e

N

Noise (Peak-to-Peak Value Not VIN = 0V — 14 — µV
Exceeded 95% of Time) 200 mV Scale

I

IN

Input Leakage Current VIN = 0V, Pins 32, 33 — 1 10 pA
Scale Factor Temperature V

= 199 mV, 0°C < TA < +70°C — 2 7 ppm/°C

IN

Coefficient External V

Power

V

COM

Common Voltage V+ to Pin 28 2.8 3.2 3.5 V
Common Sink Current ∆ Common = +0.1V — 0.6 — mA

Common Source Current ∆Common = –0.1V — 10 — µA

DGND Digital Ground Voltage V+ to Pin 36, V+ to V– = 9V 4.5 5.3 5.8 V

Sink Current ∆DGND = +0.5V — 1.2 — mA
Supply Voltage Range V+ to V

I

S

f

CLK

Supply Current Excluding Common Current V+ to V– = 9V — 0.8 1.3 mA
Clock Frequency — 120 360 kHz
V

Resistance V

DISP

DISP

Low-Battery Flag Activation Voltage V+ to V

Digital

Continuity Comparator V
Threshold Voltages V

OUT
OUT

Pull-Down Current Pins 37, 38, 39 — 2 10 µA

= 1000 mV, Range = 2V 9997 9999 10000 Counts

REF

P-P

= 0 ppm/°C

REF

–

to V

–

+

6912V

—50 —kΩ

6.3 7.2 7.7 V

Pin 27 = High 100 200 — mV
Pin 27 = Low — 200 400 mV

3-232

TELCOM SEMICONDUCTOR, INC.

4-1/2 DIGIT ANALOG-TO-DIGITAL
CONVERTER WITH ON-CHIP LCD DRIVERS

1

TC7129

ELECTRICAL CHARACTERISTICS: V

+

to V– = 9V, V

= 1V, TA = +25°C, f

REF

= 120 kHz, unless otherwise

CLK

indicated. Pin numbers refer to 40-pin DIP.

Symbol Parameter Test Conditions Min Typ Max Unit

"Weak Output" Current Pins 20, 21 Sink/Source — 3/3 — µA
Sink/Source Pin 27 Sink/Source — 3/9 — µA

Pin 22 Source Current — 40 — µA
Pin 22 Sink Current — 3 — µA

PIN CONFIGURATIONS

40

40-Pin PDIP

OSC
OSC

ANNUNICATOR DRIVE

B1, C1, CONT

A1, G1, D

F1, E1, DP

B2, C2, LO BATT

A2, G2, D

F2, E2, DP

B3, C

MINUS

DISPLAY

OUTPUT

LINES

3,

A3, G3, D

F3, E3, DP

B4, C

4, BC5

A4, G4, D

F4, E4, DP

V

DISP

DP4/OR

BP
BP
BP

1

1

2

3

3
4
5

1

6

1

7
8

2

9

2

10

TC7129CPL

11

3

12

3

13

14

4

15

4

16

3

17

2

18

1

19

20

OSC
DP

39
38

DP

37

RANGE

36

DGND
REF LO

35

REF HI

34

IN HI

33
32

IN LO

31

BUFF

C

30
29

C

28

COM
CONT

27

INT OUT

26

INT IN

25

V

24
23

V

22

LATCH/HOLD

21

DP3/UR

1
2

–

REF
+

REF

+

–

2

2

3

4

5

44-Pin QFP

, CONT

1

, C

1

B

A.D.

1

2

BP

OSC3OSC1NC

TC7129CKW

16

NC

/OR

4

DISP

V

DP

OSC2DP1DP2RANGE

/UR

3

DP

F1, E1, DP

B2, C2, BATT

A2, G2, D

F2, E2, DP

B3, C

MINUS

3,

A3, G3, D
F3, E3, DP
B4, C

4, BC5

A4, G4, D
F4, E4, DP

1

, D

1

, G

1

A

44 43 42 41 39 3840

1

1

2
3

2

4

2

5

NC

6

7

3

8

3

9

10

4

11

4

12 13 14 15 17 18

BP3BP

TELCOM SEMICONDUCTOR, INC.

37 36 35 34

19 20 21 22

–

V+V

LATCH/HOLD

DGND

33
32
31
30
29
28
27

26
25
24
23

INT IN

REF LO
REF HI
IN HI
IN LO
BUFF

NC

–

C

REF

+

C

REF

COM
CONT
INT OUT

F1, E1, DP

B2, C2, BATT

A2, G2, D

F2, E2, DP

B3, C

MINUS

3,

A3, G3, D
F3, E3, DP
B4, C

4, BC5

A4, G4, D
F4, E4, DP

1

, D

, CONT

1

1

, G

, C

1

1

A

B

6543 1442

7

1

8
9

2

10

2

11
12

NC

13

3
3

4

4

18 19 20 21 23 24

2

BP3BP

44-Pin PLCC

A.D.

OSC3OSC1NC

TC7129CLW

22

1

BP

DISP

V

/OR

4

DP

NC

OSC2DP1DP2RANGE

43 42 41 40

25 26 27 28

/UR

3

DP

LATCH/HOLD

DGND

–

V+V

INT IN

39
38
37
36
35
34
33
3214
3115
3016
2917

REF LO
REF HI
IN HI
IN LO
BUFF
NC

–

C

REF
+

C

REF

COM
CONT
INT OUT

6

7

8

3-233

4-1/2 DIGIT ANALOG-TO-DIGITAL

CONVERTER WITH ON-CHIP LCD DRIVERS

TC7129

PIN DESCRIPTIONS

Pin No. Pin No. Pin No.

40-Pin 44-Pin 44-Pin

TC7129CPL TC7129CKW TC7129CLW Symbol Function

1 40 2 OSC
2 41 3 OSC

1
3

3 ANNUNCIATOR Backplane square-wave output for driving annunciators.
4435B
5446A
617F
728B
839A
9410F

, C1, CONT Output to display segments.

1

, G1, D

1

1

, C2, LO BATT Output to display segments.

2

2

2

, E1, DP

, G2, D

, E2, DP

1

1

2

2

10 5 11 B3, C3, MINUS Output to display segments.
11 7 13 A3, G3, D
12 8 14 F3, E3, DP
13 9 15 B4, C4, BC
14 10 16 A4, D4, G
15 11 17 F4, E4, DP
16 12 18 BP
17 13 19 BP
18 14 20 BP
19 15 21 V
20 16 22 DP

21 18 24 DP

3

3
5

4

4
3
2
1

DISP

/OR Input: When HI, turns on most significant decimal point.

4

/UR Input: Second most significant decimal point on when HI.

3

22 19 25 LATCH/HOLD Input: When floating, ADC operates in the free-run mode.

23 20 26 V
24 27 V

–
+

25 21 28 INT IN Input to integrator amplifier.
26 23 29 INT OUT Output of integrator amplifier.
27 24 30 CONTINUITY Input: When LO, continuity flag on the display is OFF.

28 25 31 COMMON Sets common-mode voltage of 3.2V below V

29 26 32 C
30 27 33 C

+

REF

–

REF

31 29 35 BUFFER Output of buffer amplifier.
32 30 36 IN LO Negative input voltage terminal.
33 31 37 IN HI Positive input voltage terminal.

Input to first clock inverter.
Output of second clock inverter.

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.

Output: Pulled HI when result count exceeds ±19,999.

Output: Pulled HI when result count is less than ±1000.

When pulled HI, the last displayed reading is held. When
pulled LO, the result counter contents aren shown
inincrementing during the deintegrate 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.

When HI, continuity flag is ON.
Output: HI when voltage between inputs is less than +200
mV. LO when voltage between inputs is more than +200
mV.

10X, etc. Can be used as preregulator for external
reference.

Positive side of external reference capacitor.
Negative side of external reference capacitor.

+

for DE,

3-234

TELCOM SEMICONDUCTOR, INC.

4-1/2 DIGIT ANALOG-TO-DIGITAL
CONVERTER WITH ON-CHIP LCD DRIVERS

PIN DESCRIPTIONS

1

TC7129

Pin No. Pin No. Pin No.

40-Pin 44-Pin 44-Pin

TC7129CPL TC7129CKW TC7129CLW Symbol Function

34 32 38 REF HI Positive reference voltage in
35 33 39 REF LO Negative reference voltage
36 34 40 DGND Internal ground reference for digital section. See "±5V Power

Supply" paragraph.

37 35 41 RANGE 3 µA pull-down for 200 mV scale. Pulled HI externally for 2V

scale.
38 36 42 DP
39 37 43 DP
40 38 44 OSC

6,17, 28, 39 12, 23, 34,1 NC No Connection

2

1

2

Internal 3 µA pull-down. When HI, decimal point 2 will be on.

Internal 3 µA pull-down. When HI, decimal point 1 will be on.

Output of first clock inverter. Input of second clock inverter.

COMPONENT SELECTION

(All pin designations refer to 40-Pin Dip)

The TC7129 is designed to be the heart of a high­resolution analog measurement instrument. The only addi­tional components required are a few passive elements, a
voltage reference, an LCD, and a power source. Most
component values are not critical; substitutes can be chosen
based on the information given below.

The basic circuit for a digital multimeter application is
shown in Figure 1. See "Special Applications" for variations.
Typical values for each component are shown. The sections
below give component selection criteria.

Oscillator (X

The primary criterion for selecting the crystal oscillator
is to chose a frequency that achieves maximum rejection of
line-frequency noise. To do this, the integration phase
should last an integral number of line cycles. The integration
phase of the TC7129 is 10,000 clock cycles on the 200 mV
range and 1000 clock cycles on the 2V range. One clock
cycle is equal to two oscillator cycles. For 60 Hz rejection, the
oscillator frequency should be chosen so that the period of
one line cycle equals the integration time for the 2V range:

1/60 second = 16.7 msec =

1000 clock cycles 2 osc cycles/clock cycle

, CO1, CO2, RO)

OSC

*

oscillator frequency

,

The resistor and capacitor values are not critical; those
shown work for most applications. In some situations, the
capacitor values may have to be adjusted to compensate for
parasitic capacitance in the circuit. The capacitors can be
low-cost ceramic devices.

Some applications can use a simple RC network instead
of a crystal oscillator. The RC oscillator has more potential
for jitter, especially in the least significant digit. See "RC
Oscillator."

Integrating Resistor (R

The integrating resistor sets the charging current for
the integrating capacitor. Choose a value that provides a
current between 5 µA and 20 µA at 2V, the maximum full­scale input. The typical value chosen gives a charging
current of 13.3 µA:

I

CHARGE

Too high a value for R
noise pickup and increases errors due to leakage current.
Too low a value degrades the linearity of the integration,
leading to inaccurate readings.

2V

= 13.3 µA

150 kΩ

)

INT

increases the sensitivity to

INT

2

3

4

5

6

7

giving an oscillator frequency of 120 kHz. A similar calcula­tion gives an optimum frequency of 100 kHz for 50 Hz
rejection.

TELCOM SEMICONDUCTOR, INC.

8

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