TelCom Semiconductor Inc TC820CPL, TC820CLW, TC820CKW Datasheet

3-3/4 DIGIT A/D CONVERTER WITH FREQUENCY
COUNTER AND LOGIC PROBE

FEATURES

■ Multiple Analog Measurement System

— Digit A/D Converter
— Frequency Counter
— Logic Probe

■ Low Noise A/D Converter:

— Differential Inputs, (1pA Bias Current)
— On-Chip 50PPM/°C Voltage Reference

■ Frequency Counter:

— 4Mhz Maximum Input Frequency
— Auto-ranging Over Four Decade Range

■ Logic Probe:

— Two LCD Annunciators
— Buzzer Driver

■ 3-3/4 Digit Display with Overrange Indicator

■ LCD Display Driver with Built-in Contrast Control

■ Data Hold Input for Comparison Measurements

■ Low Battery Detect with LCD Annunciator

■ Underrange and Overrange Outputs

■ On-Chip Buzzer Driver with Control Input

■ 44-Pin Plastic Flat Pack or PLCC or 40-Pin Plastic

DIP Packages

FUNCTIONAL BLOCK DIAGRAM

LOGIC HIGH
LOGIC LOW

OVERRANGE PKHOLD LOW BATT

GENERAL DESCRIPTION

The TC820 is a 3-3/4 digit, multi-measurement system
especially suited for use in portable instruments. It inte­grates a dual slope A/D converter, auto-ranging frequency
counter and logic probe into a single 44-pin surface mount
or 40-pin through hole package. The TC820 operates from
a single 9V input voltage (battery) and features a built-in
battery low flag. Function and decimal point selection are
accomplished with simple logic inputs designed for direct
connection to an external microcontroller or rotary switch.

Ease of use, low power operation and high functional
integration make the TC820 desirable in a variety of analog
measurement applications.

ORDERING INFORMATION

Part No. Resolution Package Range

TC820CKW 3-3/4 Digits 44-Pin Plastic 0°C to +70°C

TC820CLW 3-3/4 Digits 44-Pin Plastic 0°C to +70°C

TC820CPL 3-3/4 Digits 40-Pin Plastic DIP 0°C to +70°C

TRIPLEX LCD

Quad Flat Package

Leadless Chip
Carrier

1

TC820

2

3

4

Temperature

5

LOW DRIFT VOLTAGE

DIFFERENTIAL

UNDERRANGE

EOC

OVERRANGE

ANALOG

INPUT

FULL-SCALE

SELECT

FREQUENCY

INPUT

LOGIC

PROBE

INPUT

REFERENCE

3-3/4 DIGIT

A/D CONVERTER

ANALOG GND

AUTORANGING

FREQUENCY

COUNTER

LOGIC

PROBE

DIGITAL GROUND

TELCOM SEMICONDUCTOR, INC.

CLOCK

OSCILLATOR

TC820

TO LCD
AND BUZZER

TRIPLE LCD

DRIVERS

PEAK HOLD

COMPARATOR

LOW

BATTERY

DETECT

PEAK
HOLD

ANNUNCIATOR DRIVE

DECIMAL
DRIVERS

BUZZER

FUNCTION

SELECT

+

9V

POINT

DRIVER

VOLTS
FREQUENCY
LOGIC

DECIMAL
POINT
SELECT

BUZZER
CONTROL

FUNCTION
SELECT

6

7

8

TC820-10 10/17/96

3-149

TC820

3-3/4 DIGIT A/D CONVERTER WITH

FREQUENCY AND LOGIC PROBE

GENERAL DESCRIPTION

The TC820 is a 3-3/4 digit measurement system com­bining an integrating analog-to-digital converter, frequency
counter, and logic level tester in a single package. The
TC820 supersedes the TC7106 in new designs by improv­ing performance and reducing system cost. The TC820
adds features that are difficult, expensive, or impossible to
provide with older A/D converters (see the competitive
evaluation). The high level of integration permits TC820­based instruments to deliver higher performance and more
features, while actually reducing parts count. Fabricated in
low-power CMOS, the TC820 directly drives a 3-3/4 digit
(3999 maximum) LCD.

With a maximum range of 3999 counts, the TC820
provides 10 times greater resolution in the 200mV to 400mV
range than traditional 3-1/2 digit meters. An auto-zero cycle
guarantees a zero reading with a 0V input. CMOS process­ing reduces analog input bias current to only 1pA. Rollover
error (the difference in readings for equal magnitude but
opposite polarity input signals) is less than ±1 count. Differ­ential reference inputs permit ratiometric measurements for
ohms or bridge transducer applications.

The TC820's frequency counter option simplifies design
of an instrument well-suited to both analog and digital
troubleshooting: voltage, current, and resistance measure­ments, plus precise frequency measurements to 4MHz
(higher frequencies can be measured with an external
prescaler), and a simple logic probe. The frequency counter
will automatically adjust its range to match the input fre­quency, over a four-decade range.

Two logic level measurement inputs permit a TC820­based meter to function as a logic probe. When combined
with external level shifters, the TC820 will display logic levels
on the LCD and also turn on a piezoelectric buzzer when the
measured logic level is low.

Other TC820 features simplify instrument design and
reduce parts count. On-chip decimal point drivers are in­cluded, as is a low battery detection annunciator. A piezo­electric buzzer can be controlled with an external switch or
by the logic probe inputs. Two oscillator options are pro­vided: A crystal can be used if high accuracy frequency
measurements are desired, or a simple RC option can be
used for low-end instruments.

A "peak reading hold" input allows the TC820 to retain
the highest A/D or frequency reading. This feature is useful
in measuring motor starting current, maximum tempera­ture, and similar applications.

A family of instruments can be created with the TC820.
No additional design effort is required to create instruments
with 3-3/4 digit resolution.

The TC820 operates from a single 9V battery, with
typical power of 10 mW. Packages include a 40-pin plastic
DIP, 44-pin plastic flat package, and 44-pin PLCC.

COMPETITIVE EVALUATION

Features Comparison TC820 7106

3-3/4 Digit Resolution Yes No
Auto-Ranging Frequency Counter Yes No
Logic Probe Yes No
Decimal Point Drive Yes No
Peak Reading Hold Yes No

(Frequency or Voltage)
Display Hold Yes No
Simple 10:1 Range Change Yes No
Buzzer Drive Yes No
Low Battery Detection Yes No

With Annunciator
Overrange Detection Yes No

With Annunciator
Low Drift Reference Yes No
Underrange/Overrange Yes No

Logic Output
Input Overload Display "OL" "1"
LCD Annunciator Driver Yes No
LCD Drive Type Triplexed Direct
LCD Pin Connections 15 24
LCD Elements 36 23

3-150

TELCOM SEMICONDUCTOR, INC.

3-3/4 DIGIT A/D CONVERTER WITH
FREQUENCY AND LOGIC PROBE

1

TC820

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage (VDD to GND) .....................................15V

Analog Input Voltage (Either Input) (Note 1) ....VDD to V

Reference Input Voltage (Either Input).............VDD to V

Digital Inputs ............................................... VDD to DGND

V

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

DISP

Package Power Dissipation (TA ≤ 70°C) (Note 2)

40-Pin Plastic DIP.............................................1.23W

44-Pin PLCC.....................................................1.23W

44-Pin Plastic Flat Package..............................1.00W

Operating Temperature Range

"C" Devices............................................ 0°C to +70°C

"E" Devices .......................................– 40°C to +85°C

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

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

ELECTRICAL CHARACTERISTICS: V

Symbol Parameter Test Conditions Min Typ Max Units

Zero Input Reading VIN = 0V – 000 ±000 +000 Digital

RE Roll-Over Error VIN = ±390mV – 1 ±0.2 +1 Counts

NL Nonlinearity (Maximum Full-Scale = 400mV – 1 ±0.2 +1 Count

CMRR Common-Mode Rejection V

VCMR Common-Mode Voltage Input High, Input Low V

e

N

I

IN

V

COM

V

CTC

TC

ZS

TC

FS

I

S

Deviation From Best
Straight Line Fit)

Ratiometric Reading VIN = V

Ratio Full-Scale = 400mV

Range
Noise (P-P Value Not VIN = 0V — 15 — µV

Exceeded 95% of Time) Full-Scale = 400mV
Input Leakage Current VIN = 0V

Analog Common Voltage 25 kΩ Between Common and V

Common Voltage 25 kΩ Between Common and V
Temperature Coefficient 0°C ≤ TA ≤ +70°C — 35 50 ppm/°C

Zero Reading Drift VIN = 0V

Scale Factor VIN = 399mV
Temperature Coefficient 0°C ≤ T

Supply Current VIN = 0V — 1 1.5 mA
Peak-to-Peak Backplane V

Drive Voltage V

Full Scale = 400 mV Reading

Full-Scale = 400mV

(VFS = 200 mV)

T
0°C ≤ T
– 40°C ≤ TA ≤ +85°C — 100 —

(VSS – V

– 40°C ≤ TA ≤ +85°C—50—

0°C ≤ T
– 40°C ≤ TA ≤ +85°C1

– 40°C ≤ TA ≤ +85°C—5—
Ext Ref = 0 ppm/°C

= 9V, TA = 25°C, unless otherwise specified.

S

, TC820 1999 1999/2000 2000 Digital

REF

= ±1V, VIN = 0V — 50 — µV/V

CM

= 25°C—110pA

A

≤ +70°C—20—

A

) 3.15 3.3 3.45 V

COM

≤ +70°C — 0.2 — µV/°C

A

≤ +70°C — 1 5 ppm/°C

A

= 9V 4.25 4.7 5.3 V

S

= DGND

DISP

*Static-sensitive devices. Unused devices should be stored in conductive
material to protect against 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

SS

operation of the device at these or any other conditions above those

SS

indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.

NOTES: 1. Input voltages may exceed the supply voltages provided that

input current is limited to ±100µA. Current above this value
may result in invalid display readings but will not destroy the
device if limited to ±1mA.

2. Dissipation ratings assume device is mounted with all leads
soldered to printed circuit board.

+ 1.5 — VDD– 1 V

SS

DD

DD

2

3

4

5

6

7

8

TELCOM SEMICONDUCTOR, INC.

3-151

3-3/4 A/D CONVERTER WITH

FREQUENCY COUNTER

AND LOGIC PROBE

TC820

ELECTRICAL CHARACTERISTICS (Cont.)

Symbol Parameter Test Conditions Min Typ Max Units

Buzzer Frequency f
Counter Timebase Period f
Low Battery Flag Voltage V

V

IL

V

IH

V

OL

Input Low Voltage — — DGND + 1.5 V
Input High Voltage V
Output Low Voltage, IL = 50µA — — DGND + 0.4 V

UR, OR Outputs

V

OL

Output High Voltage, IL = 50µAV
UR, OR Outputs

Control Pin VIN = V
Pull-Down Current

PIN DESCRIPTION

= 40kHz — 5 — kHz

OSC

= 40kHz — 1 — Second

OSC

DD

to V

SS

DD

6.7 7 7.3 V

– 1.5 — — V

DD

– 1.5 — — V

DD

—5 —µA

Pin No. Pin No.
(40-Pin (44-Pin Flat

Package) Package) Symbol Description

1 40 L-E4 LCD segment driver for L ("logic LOW"), polarity, and "e" segment of most

significant digit (MSD).
2 41 AGD4 LCD segment drive for "a," "g," and "d" segments of MSD.
3 42 BC4P3 LCD segment drive for "b" and "c" segments of MSD and decimal point 3.
4 43 HFE3 LCD segment drive for H ("logic HIGH"), and "f" and "e" segments of third LSD.
5 44 AGD3 LCD segment drive for "a," "g," and "d" segments of third LSD.
6 1 BC3P2 LCD segment drive for "b" and "c" segments of third LSD and decimal point 2.
7 2 OFE2 LCD segment drive for "overrange," and "f" and "e" segments of second LSD.
8 3 AGD2 LCD segment drive for "a," "g," and "d" segments of second LSD.
9 4 BC2P1 LCD segment drive for "b " and "c" segments of second LSD and decimal point 1.

10 5 PKFE1 LCD segment drive for "hold peak reading," and "f" and "e" segments of LSD.
11 6 AGD1 LCD segment drive for "a," "g," and "d" segments of LSD.
12 7 BC1BT LCD segment drive for "b" and "c" segments of LSD and "low battery."
13 8 BP3 LCD backplane #3.
14 9 BP2 LCD backplane #2.
15 10 BP1 LCD backplane #1.
—11V

DISP

16 12 DGND Internal logic digital ground, the logic "0" level. Nominally 4.7V below VDD.
17 13 ANNUNC Square-wave output at the backplane frequency, synchronized to BP1. ANNUNC

18 14 LOGIC Logic mode control input. When connected to V

19 15 RANGE/ Dual-purpose input. In range mode, when connected to VDD, the integration time

FREQ will be 200 counts instead of 2000 counts and the LCD will display the analog input

Sets peak LCD drive signal: V

PEAK

= (V

DD

) –V

DISP

. V

may also be used to

DISP

compensate for temperature variation of LCD crystal threshold voltage.

can be used to control display annunciators. Connecting an LCD segment to

ANNUNC turns it on; connecting it to its backplane turns it off.

, the converter is in logic mode.

DD

The LCD displays "OL" and the decimal point inputs control the HIGH and LOW

annunciators. When the "low" annunciator is on, the buzzer will also be on. When

unconnected or connected to DGND, the TC820 is in the voltage/frequency

measurement mode. This pin has a 5µA internal pull-down to DGND.

divided by 10. (See text for limitation withTC820.) In frequency mode, this pin is the

frequency input. A digital signal applied to this pin will be measured with a 1-second

time base. There is an internal 5µA pull-down to DGND.

3-152

TELCOM SEMICONDUCTOR, INC.

3-3/4 A/D CONVERTER WITH
FREQUENCY COUNTER
AND LOGIC PROBE

PIN DESCRIPTION

1

TC820

Pin No. Pin No.
(40-Pin (44-Pin Flat

Package) Package) Symbol Description

20 16 DP0/LO Dual-purpose input. Decimal point select input for voltage measurements. In logic

mode, connecting this pin to VDD will turn on the "low" LCD segment. There is an
internal 5µA pull-down to DGND in volts mode only. Decimal point logic:

DP1 DP0 Decimal Point Selected

0 0 None
0 1 DP1
1 0 DP2
1 1 DP3

21 17 DP1/HI Dual-purpose input. Decimal point select input for voltage measurements. In logic

mode, connecting this pin to V

internal 5µA pull-down to DGND in volts mode only.
22 18 BUZOUT Buzzer output. Audio frequency, 5kHz, output which drives a piezoelectric buzzer.
23 19 BUZIN Buzzer control input. Connecting BUZIN to V

logically ORed (internally) with the "logic level low" input. There is an internal 5µA

pull-down to DGND.
24 20 FREQ/ Voltage or frequency measurement select input. When unconnected, or connected

VOLTS to DGND, the A/D converter function is active. When connected to V

frequency counter function is active. This pin has an internal 5µA pull-down

to DGND.
25 21 PKHOLD Peak hold input. When connected to V

if a new conversion value is greater than the preceding value. Thus, the peak

reading will be stored and held indefinitely. When unconnected, or connected to

DGND, the converter will operate normally. This pin has an internal 5µA pull-down

to DGND.

22 UR Underrange output. This output will be HIGH when the digital reading is 380 counts

or less.

23 OR Overrange output. This output will be HIGH when the analog signal input is greater

than full scale. The LCD will display "OL" when the input is overranged.
26 24 V
27 25 COM Analog circuit ground reference point. Nominally 3.3V below VDD.
28 26 C
29 27 C
30 28 V
31 29 V
32 30 V
33 31 V
34 32 V
35 33 C
36 34 V

35 EOC/ Bidirectional pin. Pulses low (i.e., from V

37 36 OSC1 Crystal oscillator (input) connection.
38 37 OSC2 Crystal oscillator (output) connection.
39 38 OSC3 RC oscillator connection.
40 39 V

SS

+
REF

–
REF

+
REF

–
REF

–
IN

+
IN

BUFF

AZ

INT

HOLD conversion. If connected to VDD, conversions will continue, but the display is not

DD

Negative supply connection. Connect to negative terminal of 9V battery.

Positive connection for reference capacitor.

Negative connection for reference capacitor.

High differential reference input connection.

Low differential reference input connection.

Low analog input signal connection.

High analog input signal connection.

Buffer output. Connect to integration resistor.

Auto-zero capacitor connection.

Integrator output. Connect to integration capacitor.

updated.

Positive power supply connection, typically 9V.

will turn on the "high" LCD segment. There is an

DD

turns the buzzer on. BUZIN is

DD

, the

DD

, the converter will only update the display

DD

to DGND) at the end of each

DD

2

3

4

5

6

7

8

TELCOM SEMICONDUCTOR, INC.

3-153

TC820

PIN CONFIGURATIONS

3-3/4 A/D CONVERTER WITH

FREQUENCY COUNTER

AND LOGIC PROBE

SEGMENTS L-E4

SEGMENTS AGD4

SEGMENTS BC4P3

SEGMENTS HFE3

SEGMENTS AGD3

SEGMENTS BC3P2

SEGMENTS OFE2

SEGMENTS AGD2

SEGMENTS BCP1

SEGMENTS PKFE1

SEGMENTS AGD1

SEGMENTS BC1BT

BP3
BP2
BP1

DGND

ANNUNC

LOGIC

RANGE/FREQ

DP0/LO

1
2
3
4
5
6
7
8

9
10
11
12
13
14
15
16
17
18
19
20

TC820CPL

V

40

OSC3

39
38

OSC2
OSC1

37

V

36

C

35

V

34

V

33

V

32

V

31

V

30

C

29

28

C
COM

27

V

26
25

PK HOLD

24

FREQ/VOLTS

23

BUZ IN

22

BUZ OUT

21

DP1/HI

DD

INT
AZ

BUFF

+
IN
–
IN

–
REF

+
REF
–
REF

+
REF

SS

BC3P2

OFE2

AGD2

BC2P1
PKFE1

AGD1

BP1BT

BP3

BP2
BP1

V

DISP

BC3P2

OFE2

AGD2

BCP2P1

PKFE1

AGD1

BP1BT

BP3
BP2

BP1

V

DISP

AGD3

HFE3

BC4P3

6543 1442

7
8
9

10

11

12

13

18 19 20 21 23 24

DGND

AGD4

TC820CLW

LOGIC

ANNUNC

RANGE/FREQ

AGD3

BC4P3

HFE3

44 43 42 41 39 3840

1
2
3
4

5
6

7
8

9
10
11

12 13 14 15 17 18

AGD4

TC820CKW

L-E4

22

DP0/LO

L–E4

16

DD

V

DP1/HI

DD

V

OSC3

BUZ OUT

OSC3

OSC242OSC141EOC/HOLD

43

25 26 27 28

40

INT

V

UR

BUZ IN

PK HOLD

FREQ/VOLTS

INT

V

OSC1

OSC2

37 36 35

19 20 21 22

EOC/HOLD

34

39
38
37
36
35
34
33
3214
3115
3016
2917

33
32
31
30
29
28
27
26
25
24
23

C

AZ

V

BUFF

+

V

IN

–

V

IN

–

V

REF

+

V

REF

–

C

REF

+

C

REF

COM

V

SS

OR

C

AZ

V

BUFF

+

V

IN

–

V

IN

–

V

REF

+

V

REF

–

C

REF

+

C

REF

COM

V

SS

OR

3-154

DGND

LOGIC

ANNUNC

UR

DP1/HI

DP0/LO

RANGE/FREQ

BUZ IN

BUZ OUT

PK HOLD

FREQ/VOLTS

TELCOM SEMICONDUCTOR, INC.

3-3/4 A/D CONVERTER WITH
FREQUENCY COUNTER
AND LOGIC PROBE

FUNCTIONAL BLOCK DIAGRAM

1

TC820

2

C

V

V

+

V

REF
–

V

REF

COMMON

V

DD

V

SS

+
REF

+
IN

–
IN

–

C

REFVBUFF

C

V

AZ

INT

LOW

BATT

DETECT

A/D CONTROL

UNDERRANGE
OVERRANGE

RANGE/FREQ

TO LCD

DEINT

RANGE

INPUT

EOC

÷2

TC820

OSC3OSC2OSC1

BUZ IN

LOGIC
LOW

÷8

FREQUENCY COUNTER INPUT
A/D COUNTER SELECT

RANGE

SEL

B
A

LOW BATT

A/D COUNTER

(3999 COUNTS)

COMPARATOR
A > B

DISPLAY

LATCH

LOGIC

TRIPLEX

DRIVERS

LOW

15

BUZZER
DRIVER

RANGE/
FREQ

FREQ/
VOLTS

LOGIC

DP0/LO
DP1/HI

3

4

5

DGND

UR OR

EOC/

HOLD

PEAK
HOLD

ANNUNC

V

DISP

SEG0 • • • BP3

6

7

8

TELCOM SEMICONDUCTOR, INC.

3-155