ICL7135
ICL7135
4
�½
Digit Analog-To-Digital Converter
1.
DESCRIPTION
The ICL7135 is 4 1/2-digit, dual-slope-integrating, analog-to-digital converter (ADC) designed to provide
interfaces to both a microprocessor and a visual display. The digit-drive outputs D1 through D4 and multiplexed
binary-coded-decimal outputs B1, B2, B4, and B8 provide an interface for LED or LCD decoder/drivers as well
as microprocessors.
The ICL7135 offers 50-ppm (one part in 20,000) resolution with a maximum linearity error of one count. The zero
error is less than 10µV and zero drift is less than 0.5 µV/°C. Source-impedance errors are minimized by low input
current (less than 10 pA). Rollover error is limited to ±1 count.
The BUSY, STROBE, RUN/HOLD, OVER RANGE, and UNDER RANGE control signals support
microprocessor-based measurement systems. The control signals also can support remote data acquisition systems
with data transfer through universal asynchronous receiver transmitters (UARTs).
DIP28 OR
SOP28
PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
9
28 UNDERRANGE
27 OVERRANGE
26 STROBE
25 R/H
24 DIGITAL GND
23 POL
22 CLOCK IN
21 BUSY
20 (LSD) D1
19 D2
18 D3
17 D4
16 (MSB) B8
15 B4
2.
FEATURES
V-
•
Zero Reading for 0V Input
REFERENCE
•
Precision Null Detection With True Polarity at Zero
ANALOG COMMON
•
1pA Typical Input Leakage Current
INT OUT
•
True Differential Input
AZ IN
•
Multiplexed Binary-Coded-Decimal (BCD) Outputs
BUFF OUT
•
Low Rollover Error: ±1 Count Max
•
Control Signals Allow Interfacing With UARTs or Microprocessors
REF CAP -
•
Autoranging Capability With Over-and Under-Range Signals
REF CAP +
•
TTL-Compatible Outputs
IN LO
Ordering Information
PART NO.
ICL7135CPI
ICL7135CM
TEMP. RANGE (°C)
0 – 70 °C
0 – 70 °C
PACKAGE
28 Ld. PDIP
28 Ld. SOP28
IN HI 10
V+ 11
(MSD) D5 12
(LSB) B1 13
B2 14
Typical Application Schematic
SET V
REF
= 1.000V
V
REF
IN
100kΩ
ANALOG
GND
0.47µF
100kΩ
1µF
100kΩ
1µF
SIGNAL
INPUT
100K
0.1µF
+5V
27Ω
-5V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
ICL7135
28
27
26
25
24
23
22
21
20
19
18
17
16
15
SEVEN
SEG.
DECODE
6
0V
ANODE
DRIVER
TRANSISTORS
DISPLAY
CLOCK IN
120kHz
1
HN [ NANJING HONANO ELECTRONIC CO., LTD. ]
