Level Control and Delivery Systems Using Compensated Silicon Pressure Sensors and Precision Delta-Sigma ADCs, Part 2

This reference design describes a noncontact measurement approach for the measurement and distribution of most industrial liquids, utilizing a data acquisition system (DAS) along with a compensated silicon pressure sensor and a high-precision delta-sigma analog-to-digital converter (ADC). This document is useful for those designing a wide variety of precision-sensing and portable applications that must measure and distribute industrial liquids.

This reference design is the second in a series on compensated silicon pressure sensor applications. The first, reference design 5319, “Liquid-Level Control and Delivery System Uses a Compensated Silicon Pressure Sensor and Precision Delta-Sigma ADC, Part 1,” describes the history of measuring pressure, the modern silicon pressure sensor, and the low-cost solution of temperature-compensated pressure sensors. (The popular and cost-effective MPX2010 series silicon piezoresistive pressure sensor from Freescale® Semiconductor provides temperature compensation in the range of 0°C to +85°C, and is featured in this design.) Part 1 explains how these processors can be improved with delta-sigma ADCs before launching into a case study about the use of a modern pressure sensor and a delta-sigma ADC to measure water level.

In this document, Part 2, the system described in Part 1 is used in a noncontact measurement approach for the measurement and distribution of most industrial liquids. Here we discuss ways to resolve high-current solenoid valve and pump controls without jeopardizing the high-accuracy delta-sigma ADC-based DAS. As in Part 1, this reference design suggests system algorithms, analyzes noise, and offers calibration ideas for improving system performance while reducing complexity and cost.