Data Sheet

AD7656A

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

64 63 62

61

60 59 58

57 56 55 54 53 52 51 50 49

47

46

45

V5

42

V4

43

AGND

44

AGND

48

V6

41

40

39

V3

37

AGND

36

V2

35

34

33

V1

38

AGND

2

DB13

3

DB12

4

DB11

7

DB8/DOUT A

6

DB9/DOUT B

5

DB10/DOUT C

1

8

DGND

9

10

DB7/HBEN/DCEN

12

DB5/DCIN A

13

DB4/DCIN B

14

DB3/DCIN C

15

DB2/SEL C

16

DB1/SEL B

11

DB6/SCLK

17 18

19

20

21 22 23

24 25 26

27 28 29 30 31 32

PIN 1

AD7656A

TOP VIEW

(Not to Scale)

Figure 3. Pin Configuration

Table 5. Pin Function Descriptions1

Pin No.

Mnemonic

Description

1

Data Bit 14/Reference Buffer Enable and Disable. When SER/PAR/SEL = 0, this pin acts as a three-

state digital input/output pin.

2, 3, 64

DB13, DB12, DB15

Data Bit 13, Data Bit 12, and Data Bit 15. When SER/PAR/SEL = 0, these pins act as three-state parallel

digital input/output pins. When CS and RD are low, these pins are used to output the conversion

result. When CS and WR are low, these pins are used to write to the control register. When SER/PAR/SEL =

1, tie these pins to DGND.

4

DB11

Data Bit 11/Digital Ground. When SER/PAR/SEL = 0, this pin acts as a three-state parallel digital

output pin. When SER/PAR/SEL = 1, tie this pin to DGND.

5

DB10/DOUT C

Data Bit 10/Serial Data Output C. When SER/PAR/SEL = 0, this pin acts as a three-state parallel digital

output pin. When SER/PAR/SEL = 1 and SEL C = 1, this pin takes on its DOUT C function and outputs

serial conversion data. this pin configures the serial interface to have three DOUT x output lines.

6

DB9/DOUT B

Data Bit 9/Serial Data Output B. When SER/PAR/SEL = 0, Pin 6 acts as a three-state parallel digital

output pin. When SER/PAR/SEL = 1 and SEL B = 1, Pin 6 takes on its DOUT B function and outputs

serial conversion data. this pin configures the serial interface to have two DOUT x output lines.

7

DB8/DOUT A

Data Bit 8/Serial Data Output A. When SER/PAR/SEL = 0, this pin acts as a three-state parallel digital

output pin. When SER/PAR/SEL = 1 and SEL A = 1, this pin takes on its DOUT A function and outputs

serial conversion data.

8, 25

DGND

Digital Ground. These pins are the ground reference point for all digital circuitry on the AD7656A.

Connect both DGND pins to the DGND plane of a system. Ideally, the DGND and AGND voltages are at

the same potential and must not be more than 0.3 V apart, even on a transient basis.

9

Logic Power Supply Input. The voltage supplied at this pin determines the operating voltage of the

interface. Nominally, it is at the same supply as the supply of the host interface. Decouple this pin to

Rev. 0 | Page 7 of 28