EVAL-CN0349-PMDZ
- Reference Design
1.General Description
EVAL-CN0349-PMDZ, Evaluation Board provides a complete, robust data acquisition solution for processing conductivity cell outputs, including temperature correction. This circuit is ideal for measuring the ionic content of liquids, water quality analysis and chemical analysis. This design solution is optimized for high precision and low cost and it uses only five active devices. The circuit has a total error of less than 1% FSR after calibration. The small footprints of all the components make the circuit ideal for applications where printed circuit board (PCB) real estate is a premium. The digital output of the circuit is fully isolated, therefore, the ground loop interference is eliminated, making it ideal for harsh industrial environments
2. Features & Benefits
- • Accurate conductivity measurements to 1%
- • Small PCB footprint
- • Fully isolated
3.Circuit Description
The circuit shown in Figure 1 incorporates the AD5934 12-bit impedance converter, the ADG715 octal single-pole, single-throw (SPST) switch, the AD8606 rail-to-rail op amp, the ADuM1250 dual I2C isolator, and the ADuM5000 isolated dc-to-dc converter to create a complete data acquisition system for conductivity measurements.
The AD5934 is a high precision impedance converter system solution that combines an on-chip, programmable direct digital synthesizer (DDS) with a 12-bit, 250 kSPS analog-to-digital converter (ADC).
The AD8606 op amp was chosen because of its low offset voltage (65 μV maximum), low bias current (1 pA maximum), and low noise (12 nV/√Hz maximum).
The ADG715 is a complementary metal oxide semiconductor (CMOS), octal SPST switch that is controlled via a 2-wire serial interface that is compatible with the I2C interface standard.
Figure 1. Fully Isolated Data Acquisition System for Conductivity Measurements (Simplified Schematic: all Pins, Connections, and Decoupling not Shown)
| Manufacturer | Categories | Application |
|---|---|---|
Analog Devices |
Evaluation Development Boards, Kits, and Programmers | Measurement and Monitoring |
BOM Information
