®

4

ADS7821

Analog Input.

2

AGND1

Analog Ground. Used internally as ground reference point.

3

REF

Reference Input/Output. 2.2

µF tantalum capacitor to ground.

4

CAP

Reference Buffer Capacitor. 2.2

µF tantalum capacitor to ground.

5

AGND2

Analog Ground.

6

D15 (MSB)

O

Data Bit 15. Most Significant Bit (MSB) of conversion results. Hi-Z state when CS is HIGH, or when R/C is LOW.

7

D14

O

Data Bit 14. Hi-Z state when CS is HIGH, or when R/C is LOW.

8

D13

O

Data Bit 13. Hi-Z state when CS is HIGH, or when R/C is LOW.

9

D12

O

Data Bit 12. Hi-Z state when CS is HIGH, or when R/C is LOW.

10

D11

O

Data Bit 11. Hi-Z state when CS is HIGH, or when R/C is LOW.

11

D10

O

Data Bit 10. Hi-Z state when CS is HIGH, or when R/C is LOW.

12

D9

O

Data Bit 9. Hi-Z state when CS is HIGH, or when R/C is LOW.

13

D8

O

Data Bit 8. Hi-Z state when CS is HIGH, or when R/C is LOW.

14

DGND

Digital Ground.

15

D7

O

Data Bit 7. Hi-Z state when CS is HIGH, or when R/C is LOW.

16

D6

O

Data Bit 6. Hi-Z state when CS is HIGH, or when R/C is LOW.

17

D5

O

Data Bit 5. Hi-Z state when CS is HIGH, or when R/C is LOW.

18

D4

O

Data Bit 4. Hi-Z state when CS is HIGH, or when R/C is LOW.

19

D3

O

Data Bit 3. Hi-Z state when CS is HIGH, or when R/C is LOW.

20

D2

O

Data Bit 2. Hi-Z state when CS is HIGH, or when R/C is LOW.

21

D1

O

Data Bit 1. Hi-Z state when CS is HIGH, or when R/C is LOW.

22

D0 (LSB)

O

Data Bit 0. Lease Significant Bit (LSB) of conversion results. Hi-Z state when CS is HIGH, or when R/C is LOW.

23

BYTE

I

Swaps Pins 6 through 13 with Pins 15 through 22 when HIGH. See Figures 2 and 5.

24

R/C

I

With CS LOW and BUSY HIGH, a Falling Edge on R/C Initiates a New Conversion. With CS LOW, a rising edge on R/C

enables the parallel output.

25

CS

I

Internally OR’d with R/C. If R/C LOW, a falling edge on CS initiates a new conversion.

26

BUSY

O

At the start of a conversion, BUSY goes LOW and stays LOW until the conversion is completed and the digital outputs

have been updated.

27

Analog Supply Input. Nominally +5V. Decouple to ground with 0.1

µF ceramic and 10µF tantalum capacitors.

28

Digital Supply Input. Nominally +5V. Connect directly to pin 27. Must be

≤ V

DIGITAL

PIN #

NAME

I/O

DESCRIPTION

TABLE I. Pin Assignments.

PIN CONFIGURATION

V

DIG

V

ANA

BUSY

CS

R/C

BYTE

D0 (LSB)

D1

D2

D3

D4

D5

D6

D7

V

IN

AGND1

REF

CAP

AGND2

D15 (MSB)

D14

D13

D12

D11

D10

D9

D8

DGND

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

ADS7821