ADS8326

CS

CLK

SDO

1nF

124 W

10uF

ESR

47uF

0-4V

OPA365

REF5040

REFIN

ADS8326

REF5040

REF

V

OUT

GND

+IN

-

IN

V

IN

+5V

OPA365

Input

Signal

0Vto4V

+5V

+5V

V

DD

GND

C

BYPASS

1 F

m

R

1

50W

C

1

1.2nF

C

2

22 F

m

REF5020-EP, REF5025-EP, REF5040-EP, REF5050-EP

www.ti.com

SBOS471B – APRIL 2010 – REVISED JUNE 2015

22 kHz (LOW-PASS 30 kHz (LOW-PASS

80 kHz (LOW-

NOISE

> 500 kHz

UNIT

5-POLE)

3-POLE)

PASS 3-POLE)

GND

0.8

1

1.8

4.6

2.2 µF (ceramic)

42.5

47.2

61.2

68.3

2.2 µF + 1 µF

17.5

19.4

22.6

24.5

10 µF (ceramic)

34.4

35.6

37.7

44.5

10 µF + 1 µF

14.1

14.4

14.9

16.4

20 µF (ceramic)

34.8

34.9

35.1

35.2

20 µF + 1 µF

14.4

14.4

14.7

15.1

Adding a 1-

μF capacitor in this example filters the noise contribution of the bandgap and lowers the total noise by

a factor of 2.5 times.

8.3 System Example

8.3.1 Data Acquisition

Data acquisition systems often require stable voltage references to maintain accuracy. The REF50xx family

features low noise, very low drift, and high initial accuracy for high-performance data converters. Figure 32

shows the REF5040 in a basic data acquisition system.

Figure 32. Basic Data Acquisition System

During the design of the data acquisition system, equal consideration must be given to the buffering analog input

signal as well as the reference voltage. Having a properly designed input buffer with an associated RC filter is a

necessary requirement, but does not ensure the maximum performance.

Figure 33. Complete Data Acquisition System Using REF50xx

Three measurements using different components of the output are shown for this data acquisition system.

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