TC7126_06 Datasheet, PDF (1/26 Pages) Microchip Technology – 3-1/2 Digit Analog-to-Digital Converters

TC7126/A
3-1/2 Digit Analog-to-Digital Converters
Features:
• Internal Reference with Low Temperature Drift:
- TC7126: 80ppm/°C, Typical
- TC7126A: 35ppm/°C, Typical
• Zero Reading with Zero Input
• Low Noise: 15μV_P-P
• High Resolution: 0.05%
• Low Input Leakage Current: 1pA Typ., 10pA Max.
• Precision Null Detectors with True Polarity at Zero
• High-Impedance Differential Input
• Convenient 9V Battery Operation with Low-Power
Dissipation: 500μW Typ., 900μW Max.
Applications:
• Thermometry
• Bridge Readouts: Strain Gauges, Load Cells,
Null Detectors
• Digital Meters and Panel Meters:
- Voltage/Current/Ohms/Power, pH
• Digital Scales, Process Monitors
Device Selection Table
Package
Code
Package
Temperature
Range
CPL
IPL
CKW
CLW
40-Pin PDIP
40-Pin PDIP (TC7126 Only)
44-Pin PQFP
44-Pin PLCC
0°C to +70°C
-25°C to +85°C
0°C to +70°C
0°C to +70°C
General Description:
The TC7126A is a 3-1/2 digit CMOS Analog-to-Digital
Converter (ADC) containing all the active components
necessary to construct a 0.05% resolution measure-
ment system. Seven-segment decoders, digit and
polarity drivers, 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
count. Rollover error (the difference in readings for
equal magnitude, but opposite polarity input signals) is
below ±1 count. High-impedance differential inputs
offer 1pA leakage current and a 10¹²Î© input imped-
ance. The 15μV_P-P noise performance ensures a “rock
solid” reading, and the auto-zero cycle ensures a zero
display reading with a 0V input.
The TC7126A features a precision, low drift internal
voltage reference and is functionally identical to the
TC7126. A low drift external reference is not normally
required with the TC7126A.
© 2006 Microchip Technology Inc.
DS21458C-page 1