MCP6482-ESLASHMS datasheet(19/50 Pages) MICROCHIP

部件名	MCP6482-E/MS

功能描述	4 MHz, Low-Input Bias Current Op Amps

PDF	50 Pages

Scroll/Zoom	100%

制造商	MICROCHIP [Microchip Technology]

网页	http://www.microchip.com

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19 / 50 page

 2012-2013 Microchip Technology Inc.

DS20002322C-page 19

MCP6481/2/4

4.7.3

PH ELECTRODE AMPLIFIER

The MCP6481/2/4 op amps can be used for sensing

applications where the sensor has high output

impedance, such as a pH electrode sensor; its output

impedance is in the range of 1 M

 to 1G. The key op

amp specifications for these kinds of applications are

low-input bias current and high input impedance.

A typical sensing circuit is shown in Figure 4-12, it is

implemented with a non-inverting amplifier which has a

gain of 1+R2/R1. The input voltage error due to input

bias current is equal to IB*ROUT, which is amplified by

1+R2/R1 at the output. To minimize the voltage error

and get the VOUT with better accuracy, the IB must be

small enough.

FIGURE 4-12:

pH Electrode Amplifier.

VOUT

VIN

–

pH electrode

VSEN

VSEN is the sensed voltage by pH electrode

ROUT is the pH electrode’s output impedance

–

ROUT

MCP648X

MCP6482-E/MS 数据表(PDF) 19 Page - Microchip Technology