TC835
Personal Computer Data Acquisition A/D Converter
Features
•
•
•
•
•
•
•
•
Upgrade of Pin-Compatible TC7135, ICL7135
200 kHz Operation
Single 5V Operation With TC7660
Multiplexed BCD Data Output
UART and Microprocessor Interface
Control Outputs for Auto-Ranging
Input Sensitivity: 100 µV
No Sample and Hold Required
General Description
The TC835 is a low power, 4-1/2 digit (0.005%
resolution), BCD analog-to-digital converter (ADC) that
has been characterized for 200 kHz clock rate
operation. The five conversions per second rate is
nearly twice as fast as the ICL7135 or TC7135. The
TC835, like the TC7135, does not use the external
diode resistor rollover error compensation circuits
required by the ICL7135.
The multiplexed BCD data output is perfect for interfac-
ing to personal computers. The low cost, greater than
14-bit high-resolution and 100 µV sensitivity makes the
TC835 exceptionally cost-effective.
Microprocessor-based data acquisition systems are
supported by the BUSY and STROBE outputs, along
with the RUN/HOLD input of the TC835. The
OVERRANGE, UNDERRANGE, BUSY and RUN/
HOLD control functions, plus multiplexed BCD data
outputs, make the TC835 the ideal converter for micro-
processor-based scales, measurement systems and
intelligent panel meters.
The TC835 interfaces with full function LCD and LED
display decoder/drivers. The UNDERRANGE and
OVERRANGE outputs may be used to implement an
auto-ranging scheme or special display functions.
Applications
• Personal Computer Data Acquisition
• Scales, Panel Meters, Process Controls
• HP-IL Bus Instrumentation
Typical Application
Address Bus
Control
Data Bus
+5V
PA0
PA1
PA2
R 6522 P
PA3
PA4
PA5
PA6
PA7
CA1
CA2
HCTS157
1Y
1B
2B
2Y
3B
3Y
S
1A
2A
3A
V+ REF CAP
BUF
AZ
POL
OR
INT
UR
D5
B8 INPUT+
B4
B2
TC835
B1
V
R
D1
D2
Input
D3 Analog
Common
D4
STB
R/H
F
IN
DGND
REF Voltage
+15V -15V
DG529
D
A
D
B
Channel 1
Channel 2
Channel 3
WR
Channel 4
A
1
A
0
EN
Differential
Multiplexer
PB0 PB1 PB2 PB3
F
IN
-5V
Channel Selection
©
2007 Microchip Technology Inc.
DS21478C-page 1
TC835
Package Type
28-Pin PDIP
V-
REF IN
ANALOG
COM
INT OUT
AZ IN
BUFF OUT
C
REF-
C
REF+
–INPUT
1
2
3
4
5
6
7
8
9
28 UNDERRANGE
NC
NC
27 OVERRANGE
26 STROBE
25 RUN/HOLD
24 DIGTAL GND
23 POLARITY
NC 1
INT OUT
AZ IN
BUFF OUT
REF CAP–
REF CAP+
–INPUT
+INPUT
2
3
4
5
6
7
8
44-Pin MQFP
NC
ANALOG
COMMON
REF IN
STROBE
OR
UR
NC
44 43 42 41 40 39 38 37 36 35 34
33 NC
32 NC
31 RUN/HOLD
30 DGND
29 POLARITY
TC835CPI
22 CLOCK IN
21 BUSY
20 D1 (LSD)
19 D2
18 D3
17 D4
16 B8 (MSD)
15 B4
NC
28 CLK IN
27 BUSY
26 D1 (LSD)
25 D2
24 NC
23 NC
NC
+INPUT 10
V+ 11
(MSD) D5 12
(LSB) B1 13
B2 14
TC835CKW
V+ 9
NC 10
NC 11
12 13 14 15 16 17 18 19 20 21 22
B2
B4
D4
NC
NC
D3
(LSB) B1
(MSD) D5
(MSB) B8
NC
64-Pin MQFP
RUN/HOLD
STROBE
CLK IN
DGND
BUSY
SUB
POL
NC
NC
NC
NC
NC
NC
V–
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
NC
NC
NC
NC
NC
NC
OVERRANGE
UNDERRANGE
SUB
1
2
3
4
5
6
7
8
9
48 NC
47 NC
46 NC
45 D3
44 D4
43 B3
42 B4
41 B2
40 SUB
39 B1
38 D5
37 NC
36 NC
35 NC
34 NC
33 NC
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
BUFF OUT
NC
NC
NC
NC
NC
NC
AZ IN
SUB
INT OUT
BUF CAP+
BUF CAP–
+INPUT
–INPUT
NC
V+
TC835CBU
V– 10
REF IN 11
ANALOG COM 12
NC 13
NC 14
NC 15
NC 16
Note 1:
NC = No internal connection.
2:
Pins 9, 25, 40, and 56 are connected to the die substrate. The poteltial at these pins is approximately
V+. No external connections should be made.
DS21478C-page 2
NC
D1
D2
©
2007 Microchip Technology Inc.
TC835
1.0
ELECTRICAL
CHARACTERISTICS
† Stresses above those listed under "Absolute Maximum Rat-
ings" 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. Expo-
sure to Absolute Maximum Rating conditions for extended
periods may affect device reliability.
Absolute Maximum Ratings†
Positive Supply Voltage.....................................................+6V
Negative Supply Voltage ....................................................-9V
Analog Input Voltage (Pin 9 or 10) ..............V+ to V–
(Note 2)
Reference Input Voltage (Pin 2) ................................ V+ to V–
Clock Input Voltage ....................................................0V to V
+
Operating Temperature Range .......................... 0°C to +70°C
Storage Temperature Range.........................-65°C to +150°C
Package Power Dissipation (T
A
≤
70°C)
28-Pin Plastic DIP ..................................................... 1.14Ω
44-Pin MQFP............................................................. 1.00Ω
64-Pin MQFP............................................................. 1.14Ω
DC CHARACTERISTICS
Electrical Specifications:
Unless otherwise specified, T
A
= +25°C, F
CLOCK
= 200 kHz, V+ = +5V, V- = -5V.
Parameter
Analog
Display Reading with Zero Volt Input
Zero Reading Temperature Coefficient
Full-Scale Temperature Coefficient
Nonlinearity Error
Differential Linearity Error
Display Reading in Ratiometric Operation
± Full Scale Symmetry Error (Rollover Error)
Input Leakage Current
Noise
Digital
Input Low Current
Input High Current
Output Low Voltage
Output High Voltage;
B
1
, B
2
, B
4
, B
8
, D
1 –
D
5
Busy, Polarity, Overrange,
Underrange, Strobe
Clock Frequency
Note 1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
I
IL
I
IH
V
OL
V
OH
—
—
—
2.4
4.9
f
CLK
0
10
0.08
0.2
4.4
4.99
200
100
10
0.4
5
5
1200
μA
μA
V
V
V
kHz
V
IN
= 0V
V
IN
= +5V
I
OL
= 1.6 mA
I
OH
= 1 mA
I
OH
= 10 µA
Note 10
±FSE
I
IN
e
N
TC
Z
TC
FS
NL
DNL
-0.0000
—
—
—
—
±0.0000 +0.0000
0.5
—
0.5
0.01
2
5
1
—
Display
Reading
µV/°C
ppm/°C
Count
LSB
Display
Reading
Count
pA
μV
P-P
Note 3, Note 4
V
IN
= 0V,
(Note 5)
V
IN
= 2V;
(Note 5, Note 6
Note 7
Note 7
V
IN
= V
REF
,
(Note 3)
–V
IN
= +V
IN
,
(Note 8)
Note 4
Peak-to-Peak Value not
Exceeded 95% of Time
Sym
Min
Typ
Max
Unit
Conditions
+0.9995 +0.9998 +1.0000
—
—
—
0.5
1
15
1
10
—
Functional operation is not implied.
Limit input current to under 100 µA if input voltages exceed supply voltage.
Full scale voltage = 2V.
V
IN
= 0V.
0°C
≤
T
A
≤
+70°C.
External reference temperature coefficient less than 0.01ppm/°C.
-2V
≤
V
IN
≤
+2V. Error of reading from best fit straight line.
|V
IN
| = 1.9959.
Test circuit shown in
Figure 6-7.
Specification related to clock frequency range over which the TC835 correctly performs its various functions. Increased
errors result at higher operating frequencies.
©
2007 Microchip Technology Inc.
DS21478C-page 3
TC835
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications:
Unless otherwise specified, T
A
= +25°C, F
CLOCK
= 200 kHz, V+ = +5V, V- = -5V.
Parameter
Power Supply
Positive Supply Voltage
Negative Supply Voltage
Positive Supply Current
Negative Supply Current
Power Dissipation
Note 1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
V+
V–
I+
I–
PD
4
-3
—
—
—
5
-5
1
0.7
8.5
6
-8
3
3
30
V
V
mA
mA
mΩ
f
CLK
= 0Hz
f
CLK
= 0Hz
f
CLK
= 0Hz
Sym
Min
Typ
Max
Unit
Conditions
Functional operation is not implied.
Limit input current to under 100 µA if input voltages exceed supply voltage.
Full scale voltage = 2V.
V
IN
= 0V.
0°C
≤
T
A
≤
+70°C.
External reference temperature coefficient less than 0.01ppm/°C.
-2V
≤
V
IN
≤
+2V. Error of reading from best fit straight line.
|V
IN
| = 1.9959.
Test circuit shown in
Figure 6-7.
Specification related to clock frequency range over which the TC835 correctly performs its various functions. Increased
errors result at higher operating frequencies.
DS21478C-page 4
©
2007 Microchip Technology Inc.
TC835
2.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in
Table 2-1.
TABLE 2-1:
Pin Number
28-Pin PDIP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
PIN FUNCTION TABLE
Symbol
V-
REF IN
ANALOG COMMON
INT OUT
AZ IN
BUFF OUT
C
REF
-
C
REF
+
-INPUT
+INPUT
V+
D5
B1
B2
B4
B8
D4
D3
D2
D1
BUSY
CLOCK IN
POLARITY
Negative power supply input.
External reference input.
Reference point for REF IN.
Integrator output. Integrator capacitor connection.
Auto zero input. Auto zero capacitor connection.
Analog input buffer output. Integrator resistor connection.
Reference capacitor input. Reference capacitor negative connection.
Reference capacitor input. Reference capacitor positive connection.
Analog input. Analog input negative connection.
Analog input. Analog input positive connection.
Positive power supply input.
Digit drive output. Most Significant Digit (MSD)
Binary Coded Decimal (BCD) output. Least Significant Bit (LSB)
BCD output.
BCD output.
BCD output. Most Significant Bit (MSB)
Digit drive output.
Digit drive output.
Digit drive output.
Digit drive output. Least Significant Digit (LSD)
Busy output. At the beginning of the signal-integration phase, BUSY goes High and
remains High until the first clock pulse after the integrator zero crossing.
Clock input. Conversion clock connection.
Polarity output. A positive input is indicated by a logic High output. The polarity output is
valid at the beginning of the reference integrate phase and remains valid until determined
during the next conversion.
Digital logic reference input.
Run / Hold input. When at a logic High, conversions are performed continuously. A logic
Low holds the current data as long as the Low condition exists.
Strobe output. The STROBE output pulses low in the center of the digit drive outputs.
Over range output. A logic High indicates that the analog input exceeds the full scale input
range.
Under range output. A logic High indicates that the analog input is less than 9% of the full
scale input range.
Description
24
25
26
27
28
DGND
RUN/HOLD
STROBE
OVERRANGE
UNDERRANGE
©
2007 Microchip Technology Inc.
DS21478C-page 5
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