
2004 Microchip Technology Inc.
DS21460C-page 5
TC7135
2.0
PIN DESCRIPTIONS
The description of the pins are listed in
Table 2-1.TABLE 2-1:
PIN FUNCTION TABLE
Pin Number
28-Pin PDIP,
28-Pin PLCC
Pin Number
44-Pin MQFP*
Pin Number
64-Pin MQFP*
Symbol
Description
1
39
10
V–
Negative power supply input.
2
40
11
REF IN
External reference input.
3
41
12
ANALOG COMMON
Reference point for REF IN.
4
2
18
INT OUT
Integrator output. Integrator capacitor connection.
5
3
20
AZ IN
Auto-zero inpt. Auto-zero capacitor connection.
6
4
22
BUFF OUT
Analog input buffer output. Integrator resistor
connection.
75
23
CREF–
Reference capacitor input. Reference capacitor
negative connection.
86
26
CREF+
Reference capacitor input. Reference capacitor
positive connection.
9
7
28
–INPUT
Analog input. Analog input negative connection.
10
8
30
+INPUT
Analog input. Analog input positive connection.
11
9
32
V+
Positive power supply input.
12
14
38
D5
Digit drive output. Most Significant Digit (MSD)
13
15
39
B1
Binary Coded Decimal (BCD) output. Least Significant
bit (LSb).
14
16
41
B2
BCD output.
15
17
42
B4
BCD output.
16
18
43
B8
BCD output. Most Significant bit (MSb).
17
19
44
D4
Digit drive output.
18
20
45
D3
Digit drive output.
19
25
52
D2
Digit drive output.
20
26
53
D1
Digit drive output. Least Significant Digit (LSD).
21
27
54
BUSY
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.
22
28
55
CLOCK IN
Clock input. Conversion clock connection.
23
29
57
POLARITY
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.
24
30
58
DGND
Digital logic reference input.
25
31
59
RUN/HOLD
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.
26
36
60
STROBE
Strobe output. The STROBE output pulses low in the
center of the digit drive outputs.
27
37
7
OVERRANGE
Overrange output. A logic high indicates that the
analog input exceeds the full-scale input range.
28
38
8
UNDERRANGE
Underrange output. A logic high indicates that the
analog input is less than 9% of the full-scale input
range.
* Pins not identified or documented are NC (no connects).