TC7126 Datasheet, PDF (1/13 Pages) TelCom Semiconductor, Inc – 3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS

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TC7126
TC7126A
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS
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FEATURES
GENERAL DESCRIPTION
s Low Temperature Drift Internal Reference
TC7126 ....................................... 80 ppm/°C Typ
TC7126A ..................................... 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 and Panel Meters
— Voltage/Current/Ohms/Power, pH
s Digital Scales, Process Monitors
The TC7126A is a 3-1/2 digit CMOS analog-to-digital
converter (ADC) containing all the active components nec-
essary to construct a 0.05% resolution measurement sys-
tem. Seven-segment decoders, digit and polarity drivers,
3 ^{voltage reference, and clock circuit are integrated on-chip.}
The TC7126A directly drives a liquid crystal display (LCD),
and includes a backplane driver.
A low-cost, high-resolution indicating meter requires
only a display, four resistors, and four capacitors. The
TC7126A's extremely low power drain and 9V battery
operation make it ideal for portable applications.
The TC7126A reduces linearity error to less than 1
4 ^{count. 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 leak-
age current and a 10¹²â„¦ input impedance. The 15 µV_P-P
noise performance guarantees a "rock solid" reading, and
the auto-zero cycle guarantees a zero display reading with
a 0V input.
The TC7126A features a precision, low-drift internal
5 ^{voltage reference and is functionally identical to the TC7126.}
A low-drift external reference is not normally required with
the TC7126A.
TYPICAL OPERATING CIRCUIT
+
ANALOG
INPUT
–
1 MΩ
0.01 µF
180 kΩ
0.15 µF
0.1 µF
34
33
C_R⁺_EF C_R^–_EF
LCD
31 _VI+N
2–19 SEGMENT
22–25 DRIVE
30 _VI^–_N
32 ^ANALOG
COMMON
POL ²⁰
MINUS SIGN
BP ²¹
V+ ¹
BACKPLANE
28 _{VBUFF TC7126}
240 kΩ
0.33
µF
29 _CAZ
27 _VINT
TC7126A
V_R⁺_EF ³⁶
V_R^–_EF ³⁵
V ^{– 26}
OSC₂ OSC₃ OSC₁
10 kΩ
+
9V
1 CONVERSION/SEC
39 38 COSC 40
ROSC ^{50 pF}
TO ANALOG COMMON
(PIN 32)
560 kΩ
NOTE: Pin numbers refer to 40-pin DIP.
TELCOM SEMICONDUCTOR, INC.
ORDERING INFORMATION
PART CODE
TC7126X X XXX
A or blank*
R (reversed pins) or blank (CPL pkg only)
* "A" parts have an improved reference TC
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Package Code (see below):
Package
Code
Package
Temperature
Range
CKW
CLW
CPL
IPL
44-Pin PQFP
0°C to +70°C
44-Pin PLCC
40-Pin PDIP
0°C to +70°C
0°C to +70°C
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40-Pin PDIP (non-A only) – 25°C to +85°C
AVAILABLE PACKAGES
40-Pin Plastic DIP
44-Pin Plastic Quad Flat 44-Pin Plastic Chip
Package Formed Leads Carrier PLCC
TC7126/A-8 11/6/96
3-217
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