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TC7136
TC7136A
LOW POWER, 3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS
FEATURES
s
s
Fast Overrange Recovery, Guaranteed First
Reading Accuracy
Low Temperature Drift Internal Reference
TC7136 ....................................... 70 ppm/
°
C Typ
TC7136A ..................................... 35 ppm/
°
C Typ
Guaranteed Zero Reading With Zero Input
Low Noise .................................................... 15
µ
V
P-P
High Resolution .............................................. 0.05%
Low Input Leakage Current ...................... 1 pA Typ
10 pA Max
Precision Null Detectors With True Polarity at
Zero
High-Impedance Differential Input
Convenient 9V Battery Operation With
Low Power Dissipation ........................ 500
µ
W Typ
900
µ
W Max
Thermometry
Bridge Readouts: Strain Gauges, Load Cells, Null
Detectors
Digital Meters: Voltage/Current/Ohms/Power, pH
Digital Scales, Process Monitors
Portable Instrumentation
GENERAL DESCRIPTION
The TC7136 and TC7136A are low-power, 3-1/2 digit
with liquid crystal display (LCD) drivers with analog-to-
digital converters. These devices incorporate an "integra-
tor output zero" phase which guarantees overrange
recovery. The performance of existing TC7126, TC7126A
and ICL7126-based systems may be upgraded with minor
changes to external, passive components.
The TC7136A has an improved internal zener refer-
ence voltage circuit which maintains the analog common
temperature drift to 35 ppm/°C (typical) and 75 ppm/°C
(maximum). This represents an improvement of two to four
times over similar 3-1/2 digit converters. The costly, space-
consuming external reference source may be removed.
The TC7136/A limits linearity error to less than 1 count
on 200 mV or 2V full-scale ranges. Roll-over error — the
difference in readings for equal magnitude but opposite
polarity input signals — is below
±1
count. High-impedance
differential inputs offer 1 pA leakage currents and a 10
12
Ω
input impedance. The differential reference input allows
ratiometric measurements for ohms or bridge transducer
measurements. The 15
µV
P-P
noise performance guaran-
tees a "rock solid" reading. The auto-zero cycle guarantees
a zero display readout for a 0V input.
TYPICAL OPERATING CIRCUIT
0.1 µF
34
C+
31
33
C–
2
3
4
5
6
BACKPLANE
+
9V
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s
s
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TYPICAL APPLICATIONS
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ORDERING INFORMATION
PART CODE
TC7136X X XXX
A or blank*
R (reversed pins) or blank (CPL pkg only)
* "A" parts have an improved reference TC
Package Code
(see below):
Package
Code
Package
CKW
CLW
CPL
44-Pin PQFP
44-Pin PLCC
40-Pin PDIP
1 MΩ
+
ANALOG
INPUT
–
0.01 µF
REF
REF
LCD
9–19 SEGMENT
22–25 DRIVE
POL
BP
V+
20
21
1
240 kΩ
36
10 kΩ
MINUS SIGN
+
V
IN
–
30 V
IN
32 ANALOG
COMMON
28
V
BUFF
Pin Layout
Formed Leads
—
Normal
Temperature
Range
0°C to +70°C
0°C to +70°C
0°C to +70°C
180 kΩ
0.47
µF
29
TC7136
TC7136A
+
V
REF
–
C
AZ
AVAILABLE PACKAGES
0.15 µF
V
REF
35
27
26
V
INT
V
–
OSC
2
OSC
3
OSC
1
39
38 COSC 40
ROSC 50 pF
7
1 CONVERSION/SEC
TO ANALOG COMMON
(PIN 32)
40-Pin Plastic DIP
44-Pin Plastic Quad Flat
Package Formed Leads
44-Pin Plastic Chip
Carrier PLCC
560 kΩ
8
TC7136-6
10/18/96
TELCOM SEMICONDUCTOR, INC.
3-247
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
