TC820
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 Over Range Indicator
• LCD Display Driver with Built-in Contrast Control
• Data Hold Input for Comparison Measurements
• Low Battery Detect with LCD Annunciator
• Under Range and Over Range Outputs
• On-Chip Buzzer Driver with Control Input
• 40-Pin Plastic DIP, 44-Pin Plastic Flat Pack, or
44-Pin PLCC Packages
General Description
The TC820 is a 3-3/4 digit, multi-measurement system
especially suited for use in portable instruments. It inte-
grates a dual slope A/D converter, auto-ranging fre-
quency 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 (bat-
tery) and features a built-in battery low flag. Function
and decimal point selection are accomplished with sim-
ple logic inputs designed for direct connection to an
external microcontroller or rotary switch.
Device Selection Table
Part
Number
TC820CPL
TC820CKW
TC820CLW
Resolution
3-3/4 Digits
3-3/4 Digits
3-3/4 Digits
Package
40-Pin PDIP
44-Pin PQFP
44-Pin PLCC
Operating
Temp. Range
0°C to +70°C
0°C to +70°C
0°C to +70°C
2002 Microchip Technology Inc.
DS21476B-page 1
©
TC820
Package Type
EOC/HOLD
41
44-Pin PLCC
BC4P3
AGD3
OSC3
OSC2
AGD4
OSC1
HFE3
L-E4
V
DD
6
5
4
3
2
1
44
43
42
40
BC3P2
OFE2
AGD2
V
INT
39
C
AZ
38
V
BUFF
37
V
IN
+
36
V
IN
-
35
V
REF
-
34
V
REF
+
33
C
REF
-
32
C
REF
+
31
COM
30
V
SS
29
OR
7
8
9
BC2P1
10
PKFE1
11
AGD1
12
TC820CLW
BP1BT
13
40-Pin PDIP
Segments L-E4
Segments AGD4
Segments BC4P3
Segments HFE3
Segments AGD3
Segments BC3P2
Segments OFE2
Segments AGD2
Segments BC2P1
1
2
3
4
5
6
7
8
9
40 V
DD
39
OSC3
BP3
14
BP2
15
BP1
16
38 OSC2
37 OSC1
36 V
INT
35 C
AZ
34 V
BUFF
33 V
IN
+
32 V
IN
-
V
DISP
17
18 19
20
21
22
23
24
25
26
27
28
ANNUNC
DP0/LO
DGND
LOGIC
DP1/HI
BUZOUT
RANGE/FREQ
BUZIN
FREQ/VOLTS
PKHOLD
UR
EOC/HOLD
44-Pin PQFP
BC4P3
AGD3
AGD4
OSC3
OSC2
OSC1
HFE3
L–E4
V
DD
Segments PKFE1 10
Segments AGD1 11
TC820CPL
31 V
REF
-
30 V
REF
+
29 C
REF
-
28 C
REF
+
27 COM
26 V
SS
25 PKHOLD
24 FREQ/VOLTS
23 BUZIN
22 BUZOUT
21 DP1/HI
V
INT
Segments BC1BT 12
BP3 13
BP2 14
33
C
AZ
32
V
BUFF
31
V
IN
+
30
V
IN
-
29
V
REF
-
44 43
42
41 40 39
38
37
36
35
34
BC3P2
1
OFE2
2
AGD2
3
BC2P1
4
PKFE1
5
AGD1
6
BC1BT
7
BP3
8
BP2
9
BP1
10
V
DISP
11
12 13
14
15
16
17
18
19
BP1 15
DGND 16
ANNUNC 17
LOGIC 18
RANGE/FREQ 19
DP0/LO 20
TC820CKW
28
V
REF
+
27
C
REF
-
26
C
REF
+
25
COM
24
V
SS
23
OR
20
21 22
RANGE/FREQ
FREQ/VOLTS
BUZOUT
LOGIC
DP0/LO
DP1/HI
BUZIN
ANNUNC
PKHOLD
DGND
©
DS21476B-page 2
UR
2002 Microchip Technology Inc.
TC820
Typical Applications
Triplex LCD
Logic High
Logic Low
Over Range
PKHold
Low Batt
Annunciator Drive
Low Drift Voltage
Differential
Reference
Clock
Oscillator
Triple LCD
Drivers
EOC
Under Range
Over Range
Analog Input
3-3/4 Digit A/D
Converter
Analog GND
Peak Hold
Comparator
Decimal
Point
Drivers
Decimal
Point
Select
Full Scale Select
Auto-Ranging
Frequency
Counter
TC820
Frequency Input
Low
Battery
Detect
Buzzer
Driver
Buzzer
Control
Logic Probe
Input
Logic Probe
Digital Ground
To LCD
and Buzzer
Function
Select
Volts
Frequency
Logic
Function
Select
+
Peak
Hold
9V
C
REF
+
C
REF
- V
BUFF
C
AZ
V
INT
OSC1
OSC2
OSC3
Logic
Low
BUZIN
V
IN
+
V
IN
-
V
REF
+
V
REF
-
Common
V
DD
Low
Batt
Detect
To LCD
SEL
B
A
A/D Control
DEINT
Under Range
Over Range
EOC
Range
Range Frequency
Input
÷2
÷8
Frequency Counter Input
A/D Counter Select
Range
A/D Counter
(3999 Counts)
Buzzer
Driver
Range/
Frequency
Frequency/
Volts
TC820
Comparator
A>B
Display
Latch
Logic
Low
Low Batt
Triples
Drivers
15
Logic
DP0/LO
DP1/HI
V
SS
DGND UR OR
EOC/
HOLD
PEAK
HOLD
ANNUNC
V
DISP
SEG0 • • • BP3
2002 Microchip Technology Inc.
DS21476B-page 3
©
TC820
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
DD
to GND) ................................ 15V
Analog Input Voltage:
(Either Input)
(Note 1)
............................ V
DD
to V
SS
Reference Input Voltage (Either Input) ....... V
DD
to V
SS
Digital Inputs........................................... V
DD
to DGND
V
DISP
....................................... V
DD
to (DGND – 0.3V)
Package Power Dissipation (T
A
– 70°C)
(Note 2):
40-Pin Plastic DIP ......................................... 1.23W
44-Pin PLCC ..................................................1.23W
44-Pin Plastic Flat Package (PQFP) ..............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
TC820 ELECTRICAL SPECIFICATIONS
Electrical Characteristics:
V
S
= 9V, T
A
= 25°C, unless otherwise specified.
Symbol
Parameter
Zero Input Reading
RE
NL
Rollover Error
Nonlinearity
(Maximum Deviation From Best
Straight Line Fit)
Ratiometric Reading
CMRR
Common Mode Rejection Ratio
Min
-000
-1
-1
Typ
±000
±0.2
±0.2
Max
+000
+1
+1
Units
Digital
Reading
Counts
Count
Test Conditions
V
IN
= 0V
Full Scale = 400mV
V
IN
= ±390mV
Full Scale = 400mV
Full Scale = 400mV
1999
—
1999/2000
50
2000
—
—
µV/V
V
IN
= V
REF
, TC820
V
CM
= ±1V, V
IN
= 0V
Full Scale = 400mV
(V
FS
= 200mV)
Input High, Input Low
V
IN
= 0V
Full Scale = 400mV
V
IN
= 0V
T
A
= 25°C
0°C
≤
T
A
≤
+70°C
-40°C
≤
T
A
≤
+85°C
25kΩ between Common and
V
DD
(V
SS
- V
COM
)
25kΩ Between Common and
V
DD
0°C
≤
T
A
≤
+70°C
-40°C
≤
T
A
≤
+85°C
VCMR
e
N
I
IN
Common Mode Voltage Range
Noise (P-P Value Not
Exceeded 95% of Time)
Input Leakage Current
V
SS
+ 1.5
—
—
—
—
—
—
15
—
1
20
100
3.3
—
35
50
V
DD
– 1
—
—
10
—
—
3.45
—
50
—
µV
—
pA
pA
pA
V
—
ppm/°C
—
V
COM
V
CTC
Analog Common Voltage
Common Voltage Temperature
Coefficient
3.15
—
—
—
Note 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.
©
DS21476B-page 4
2002 Microchip Technology Inc.
TC820
TC820 ELECTRICAL SPECIFICATIONS (CONTINUED)
Electrical Characteristics:
V
S
= 9V, T
A
= 25°C, unless otherwise specified.
Symbol
TC
ZS
Parameter
Zero Reading Drift
Min
—
—
—
TC
FS
Scale Factor Temperature
Coefficient
—
—
—
I
S
Supply Current
Peak-to-Peak Backplane
Drive Voltage
Buzzer Frequency
Counter TIme-Base Period
Low Battery Flag Voltage
V
IL
V
IH
V
OL
Input Low Voltage
Input High Voltage
Output Low Voltage,
UR, OR Outputs
Control Pin Pull-down Current
—
4.25
—
—
6.7
—
V
DD
– 1.5
V
DD
– 1.5
—
Typ
—
0.2
1
—
1
5
1
4.7
5
1
7
—
—
—
5
Max
—
—
—
—
5
—
1.5
5.3
—
—
7.3
DGND + 1.5
—
DGND + 0.4
—
Units
—
—
—
—
ppm/°C
ppm/°C
mA
V
kHz
Second
V
V
V
V
µA
I
L
= 50µA
V
IN
= V
DD
Test Conditions
V
IN
= 0V
0°C
≤
T
A
≤
+70°C
-40°C
≤
T
A
≤
+85°C
V
IN
= 399mV
0°C
≤
T
A
≤
+70°C
-40°C
≤
T
A
≤
+85°C
Ext Ref = 0ppm/°C
V
IN
= 0V
V
S
= 9V
V
DISP
= DGND
F
OSC
= 40kHz
F
OSC
= 40kHz
V
DD
to V
SS
Note 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.
2002 Microchip Technology Inc.
DS21476B-page 5
©
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