TC7135
4-1/2 Digit A/D Converter
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
Low Rollover Error: ±1 Count Max
Nonlinearity Error: ±1 Count Max
Reading for 0V Input
True Polarity Indication at Zero for Null Detection
Multiplexed BCD Data Output
TTL-Compatible Outputs
Differential Input
Control Signals Permit Interface to UARTs and
Microprocessors
Blinking Display Visually Indicates Overrange
Condition
Low Input Current: 1 pA
Low Zero Reading Drift: 2 µV/°C
Auto-Ranging Supported with Overrange and
Underrange Signals
Available in PDIP and Surface-Mount Packages
General Description
The TC7135 4-1/2 digit A/D Converter (ADC) offers
50 ppm (1 part in 20,000) resolution with a maximum
nonlinearity error of 1 count. An auto-zero cycle
reduces zero error to below 10 µV and zero drift to
0.5 µV/°C. Source impedance errors are minimized by
a 10 pA maximum input current. Rollover error is
limited to ±1 count.
Microprocessor-based measurement systems are
supported by the BUSY, STROBE and RUN/HOLD
control signals. Remote data acquisition systems with
data transfer via UARTs are also possible. The addi-
tional control pins and multiplexed BCD outputs make
the TC7135 the ideal converter for display or
microprocessor-based measurement systems.
Applications
• Precision Analog Signal Processor
• Precision Sensor Interface
• High Accuracy DC Measurements
Functional Block Diagram
Set V
REF
= 1V
V
REF
IN
100 kΩ
5V
1
2
V–
TC7135
UNDERRANGE
28
REF IN
27
OVERRANGE
3 ANALOG
26
STROBE
COMMON
Analog GND
4
25
RUN/HOLD
INT OUT
1 µF
24
0.47 µF
5
DIGTAL GND
AZ IN
23
6
BUFF OUT POLARITY
22
100 kΩ
7
CLOCK IN
C
REF
–
Signal
21
1 µF 8
100 kΩ
BUSY
Input
C
REF
+
9
20
(LSD) D1
–INPUT
19
0.1 µF
10
D2
+INPUT
18
11
D3
+5V
V+
12
17
D4
D5 (MSD)
13
16
(MSB) B8
B1 (LSB)
14
15
B4
B2
Clock Input
120 kHz
2004 Microchip Technology Inc.
DS21460C-page 1
TC7135
Package Types
28-Pin PLCC
INT OUT
ANALOG
COM
REF IN
STROBE
44-Pin MQFP
DIGITAL GND
RUN/HOLD
POLARITY
CLOCK IN
V–
OR
UR
NC
NC
NC
AZ IN 5
BUFF OUT 6
REF CAP– 7
REF CAP+ 8
–INPUT 9
+INPUT 10
V+ 11
12 13 14 15 16 17 18
D4
(MSD) D5
(MSB) B8
(LSB) B1
D3
B2
B4
25 RUN/HOLD
24 DIGTAL GND
23 POLARITY
NC 34
NC 35
STROBE 36
OVERRANGE 37
UNDERRANGE 38
V– 39
REF IN 40
COMMON ANALOG 41
NC 42
NC 43
NC 44
33 32 31 30 29 28 27 26 25 24 23
22 NC
21 NC
20 D3
19 D4
18 B8
TC7135
22 CLOCK IN
21 BUSY
20 D1 (LSD)
19 D2
TC7135
NC
17 B4
16 B2
15 B1
14 D5
13 NC
12 NC
NC
NC
NC
NC
NC
48 NC
47 NC
46 NC
45 D3
44 D4
43 B8
42 B4
41 B2
40 NC
39 B1
38 D5
37 NC
36 NC
35 NC
34 NC
33 NC
V+
D1
1
NC
2
INT OUT
3
4
BUFF OUT
D2
8
4
3
2
1 28 27 26
BUSY
5
C
REF
–
6
C
REF
+
7
–INPUT
9 10 11
V+
NC
D2
28-Pin PDIP
RUN/HOLD
STROBE
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
27 OVERRANGE
NC
NC
NC
NC
26 STROBE
25 RUN/HOLD
24 DIGiTAL GND
23 POLARITY
NC 1
NC 2
NC 3
NC 4
NC 5
NC 6
OVERRANGE 7
UNDERRANGE 8
NC 9
V– 10
REF IN 11
ANALOG COM 12
NC 13
NC 14
NC 15
NC 16
64-Pin MQFP
CLOCK IN
DGND
POL
BUSY
+INPUT
–INPUT
D1
AZ IN
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
l
TC7135
22 CLOCK IN
21 BUSY
20 D1 (LSD)
19 D2
18 D3
17 D4
16 B8 (MSB)
15 B4
+INPUT 10
V+ 11
(MSD) D5 12
(LSB) B1 13
B2 14
TC7135
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
C
REF
–
NC
NC
NC
NC
AZ IN
NC
C
REF
+
NC
INT OUT
BUFF OUT
+INPUT
NOTE:
NC = No internal connection.
DS21460C-page 2
NC
2004 Microchip Technology Inc.
NC
TC7135
1.0
ELECTRICAL SPECIFICATIONS
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 PDIP .......................................................... 1.14Ω
28-Pin PLCC ......................................................... 1.00Ω
44-Pin MQFP..........................................................................
64-Pin MQFP ........................................................ 1.14Ω
†
Notice:
Stresses above those listed under "Absolute Maxi-
mum 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.
DC CHARACTERISTICS
Electrical Specifications:
Unless otherwise indicated, T
A
= +25°C, F
CLOCK
= 120 kHz, V+ = +5V, V- = -5V.
(see
Functional Block Diagram).
Parameters
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:
F
CLK
I
IL
I
IH
V
OL
V
OH
—
—
—
2.4
4.9
10
0.08
0.2
4.4
4.99
100
10
0.4
5
5
µA
µA
V
V
V
V
IN
= 0V
V
IN
= +5V
I
OL
= 1.6 mA
I
OH
= 1 mA
I
OH
= 10 µA
±FSE
I
IN
e
N
TC
Z
TC
FS
NL
DNL
-0.0000
—
—
—
—
+0.9996
—
—
—
±0.0000
0.5
—
0.5
0.01
+0.0000
2
5
1
—
Display Reading
µV/°C
ppm/°C
Count
LSB
Display Reading
Count
pA
µV
P-P
Note 2, Note 3
V
IN
= 0V,
(Note 4)
V
IN
= 2V,
(Note 4, Note 5)
Note 6
Note 6
V
IN
= V
REF,
(Note 2)
-V
IN
= +V
IN,
(Note 7)
Note 3
Peak-to-Peak Value not
Exceeded 95% of Time
Sym
Min.
Typ.
Max.
Units
Conditions
+0.9999 +1.0000
0.5
1
15
1
10
—
0
200
1200
kHz
Note 8
Limit input current to under 100 µA if input voltages exceed supply voltage.
Full-scale voltage = 2V
V
IN
= 0V
30°C
≤
T
A
≤
+70°C
External reference temperature coefficient less than 0.01 ppm/°C.
-2V
≤
V
IN
≤
+2V. Error of reading from best fit straight line.
IV
IN
| = 1.9959
Specification related to clock frequency range over which the
TC7135
correctly performs its various functions.
Increased errors result at higher operating frequencies.
2004 Microchip Technology Inc.
DS21460C-page 3
TC7135
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications:
Unless otherwise indicated, T
A
= +25°C, F
CLOCK
= 120 kHz, V+ = +5V, V- = -5V.
(see
Functional Block Diagram).
Parameters
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:
V+
V-
I+
I-
PD
4
-3
—
—
—
5
-5
1
0.7
8.5
6
-8
3
3
30
V
V
mA
mA
mW
F
CLK
= 0 Hz
F
CLK
= 0 Hz
F
CLK
= 0 Hz
Sym
Min.
Typ.
Max.
Units
Conditions
Limit input current to under 100 µA if input voltages exceed supply voltage.
Full-scale voltage = 2V
V
IN
= 0V
30°C
≤
T
A
≤
+70°C
External reference temperature coefficient less than 0.01 ppm/°C.
-2V
≤
V
IN
≤
+2V. Error of reading from best fit straight line.
IV
IN
| = 1.9959
Specification related to clock frequency range over which the
TC7135
correctly performs its various functions.
Increased errors result at higher operating frequencies.
DS21460C-page 4
2004 Microchip Technology Inc.
TC7135
2.0
PIN DESCRIPTIONS
The description of the pins are listed in Table 2-1.
TABLE 2-1:
Pin Number
28-Pin PDIP,
28-Pin PLCC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
PIN FUNCTION TABLE
Pin Number
44-Pin MQFP*
39
40
41
2
3
4
5
6
7
8
9
14
15
16
17
18
19
20
25
26
27
Pin Number
64-Pin MQFP*
10
11
12
18
20
22
23
26
28
30
32
38
39
41
42
43
44
45
52
53
54
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
Description
Negative power supply input.
External reference input.
Reference point for REF IN.
Integrator output. Integrator capacitor connection.
Auto-zero inpt. 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.
Overrange output. A logic high indicates that the
analog input exceeds the full-scale input range.
Underrange output. A logic high indicates that the
analog input is less than 9% of the full-scale input
range.
22
23
28
29
55
57
CLOCK IN
POLARITY
24
25
30
31
58
59
DGND
RUN/HOLD
26
27
28
36
37
38
60
7
8
STROBE
OVERRANGE
UNDERRANGE
*
Pins not identified or documented are NC (no connects).
2004 Microchip Technology Inc.
DS21460C-page 5
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