TC7136 Datasheet, PDF (1/12 Pages) TelCom Semiconductor, Inc – LOW POWER, 3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS

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TC7136
TC7136A
LOW POWER, 3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS
FEATURES
GENERAL DESCRIPTION
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s Fast Overrange Recovery, Guaranteed First
Reading Accuracy
s Low Temperature Drift Internal Reference
TC7136 ....................................... 70 ppm/°C Typ
TC7136A ..................................... 35 ppm/°C Typ
s Guaranteed Zero Reading With Zero Input
s Low Noise .................................................... 15 µV_P-P
s High Resolution .............................................. 0.05%
s Low Input Leakage Current ...................... 1 pA Typ
10 pA Max
s Precision Null Detectors With True Polarity at
Zero
s High-Impedance Differential Input
s Convenient 9V Battery Operation With
Low Power Dissipation ........................ 500 µW Typ
900 µW Max
TYPICAL APPLICATIONS
s Thermometry
s Bridge Readouts: Strain Gauges, Load Cells, Null
Detectors
s Digital Meters: Voltage/Current/Ohms/Power, pH
s Digital Scales, Process Monitors
s Portable Instrumentation
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
3 ^{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.
4 ^{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 10¹²â„¦
input impedance. The differential reference input allows
ratiometric measurements for ohms or bridge transducer
measurements. The 15 µV_P-P noise performance guaran-
5 ^{tees a "rock solid" reading. The auto-zero cycle guarantees}
a zero display readout for a 0V input.
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
Pin Layout
Temperature
Range
CKW
CLW
CPL
44-Pin PQFP
44-Pin PLCC
40-Pin PDIP
Formed Leads
—
Normal
0°C to +70°C
0°C to +70°C
0°C to +70°C
AVAILABLE PACKAGES
40-Pin Plastic DIP
44-Pin Plastic Quad Flat 44-Pin Plastic Chip
Package Formed Leads
Carrier PLCC
TELCOM SEMICONDUCTOR, INC.
TYPICAL OPERATING CIRCUIT
0.1 µF
+
ANALOG
INPUT
–
1 MΩ
0.01 µF
180 kΩ
0.15 µF
34
33
C_R⁺_EF C_R^–_EF
LCD
31 _VI+N
9–19 SEGMENT
22–25 DRIVE
30 _VI^–_N
32 ^ANALOG
COMMON
POL ²⁰
BP ^{21 MINUS SIGN}
V+ ¹
BACKPLANE
28 _{VBUFF TC7136}
240 kΩ
0.47
µF
29 _CAZ
27 _VINT
TC7136A
V_R⁺_EF ³⁶
V_R^–_EF ³⁵
V ^{– 26}
OSC₂ OSC₃ OSC₁
+
9V
10 kΩ
1 CONVERSION/SEC
39 38 COSC 40
ROSC ^{50 pF}
TO ANALOG COMMON
(PIN 32)
6
7
560 kΩ
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TC7136-6 10/18/96
3-247