MPXM2102AS datasheet(564/670 Pages) MOTOROLA

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Motorola Sensor Device Data

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AN4010

Low-Pressure Sensing Using

MPX2010 Series Pressure Sensors

Prepared by: Memo Romero and Raul Figueroa

Motorola Sensor Products Division

Systems and Applications Engineering

INTRODUCTION

This application note presents a design for a low pressure

evaluation board using Motorola MPX2010 series pressure

sensors. By providing large gain amplification and allowing for

package flexibility, this board is intended to serve as a

design-in tool for customers seeking to quickly evaluate this

family of pressure sensors.

The MPX2010 family of pressure sensors appeals to

customers needing to measure small gauge, vacuum, or

differential pressures at a low cost. However, different

applications present design–in challenges for these sensors.

For very low pressure sensing, large signal amplification is

required, with gains substantially larger than what is provided

in Motorola’s current integrated pressure sensor portfolio. In

terms of packaging, customers often need more mechanical

flexibility such as smaller size, dual porting or both. In many

cases, customers often lack the engineering resources, time

or expertise to evaluate the sensor.

The low-pressure

evaluation board, shown in Figure 1, facilitates the

design-in-process by providing large signal gain and by

providing for different package designs in a relatively small

footprint.

CIRCUIT DESCRIPTION

For adequate and stable signal gain and output flexibility, a

two–stage differential op-amp circuit with analog or switch

output is utilized, as shown in Figure 2. The four op-amps are

packaged in a single 14 pin quad package. There are several

features to note about the circuitry.

The first gain stage is accomplished by feeding both

pressure sensor outputs (VS– & VS+) into the non-inverting

inputs of operational amplifiers. These op-amps are used in

the standard non-inverting feedback configuration. With the

condition that Resistors R2=R3, and R1=R4 (as closely as

possible), this configuration results in a gain of G1= R4/R3+1.

The default gain is 101, but there are provisions for easily

changing this value. The signal V (op-amp Pin 7) is then

calculated as:

V1 = G1*(VS+ – VS–) + Voffset. ….Equation (1)

Figure 1. Low Pressure Evaluation Board

MOTOROLA

SEMICONDUCTOR APPLICATION NOTE

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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