Microchip MCP9801 Handleiding

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 2010-2015 Microchip Technology Inc.DS00001001C-page 1

AN1001

INTRODUCTION

Microchip Technology Inc. provides a number of analog

and serial output Integrated Circuit (IC) temperature

sensors. Typically, these sensors are accurate at room

temperature within one degree Celsius (±1°C). How-

ever, at hot or cold temperature extremes, the accuracy

decreases nonlinearly. Normally, that nonlinearity has a

parabolic shape.

This application note derives an equation to describe

the typical nonlinear characteristics of a sensor, which

is used to determine compensation for the sensor's

accuracy error over a specified range of operating tem-

peratures. A PIC®microcontroller unit (MCU) can

compute the equation and provide a temperature read-

ing with higher accuracy.

This application note is based on MCP9700 and

MCP9701 analog-output temperature sensors and

MCP9800 serial-output temperature sensors.

SOLUTION APPROACH

Silicon characterization data is used to determine the

nonlinear sensor characteristics. From this data, an

equation is derived that describes the typical perfor-

mance of a sensor. When the corresponding coeffi-

cients for the equation are determined, the coefficients

are used to compute the compensation for the typical

sensor’s nonlinearity.

The error distribution is provided using an average and

±1 standard deviation (± before and after compensa-

tion. A total of 100 devices were used as representative

for the MCP9700 and MCP9701, while 160 devices

were used for the MCP9800.

Figure 1 shows the typical sensor accuracy before and

after compensation. It illustrates that the compensation

provides an accurate and linear temperature reading

over the sensor operating temperature range.

A PIC MCU is used to compute the equation and

compensate the sensor output to provide a linear

temperature reading.

FIGURE 1:Typical Sensor Accuracy Before and After Compensation.

Author:Ezana Haile

Microchip Technology Inc.

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Temperature (°C)

Typical Accuracy (°C)

Sensor Accuracy

Compensated Sensor Accuracy

IC Temperature Sensor Accuracy Compensation

with a PIC® Microcontroller

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