Data Sheet

AD7984

Rev. B | Page 7 of 24

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

Figure 4. 10-Lead MSOP Pin Configuration

Figure 5. 10-Lead LFCSP Pin Configuration

Table 6. Pin Function Descriptions

Pin No.

Mnemonic

Description

1

REF

AI

Reference Input Voltage. The REF range is 2.9 V to 5.1 V. This pin is referred to the GND pin and

should be decoupled closely to the GND pin with a 10 μF capacitor.

2

VDD

P

Power Supply.

3

IN+

AI

Differential Positive Analog Input.

4

IN−

AI

Differential Negative Analog Input.

5

GND

P

Power Supply Ground.

6

CNV

DI

Convert Input. This input has multiple functions. On its rising edge, it initiates the conversions

and selects the interface mode of the part: chain mode or CS mode. In CS mode, the SDO pin is

enabled when CNV is low. In chain mode, the data should be read when CNV is high.

7

SDO

DO

Serial Data Output. The conversion result is output on this pin. It is synchronized to SCK.

8

SCK

DI

Serial Data Clock Input. When the part is selected, the conversion result is shifted out by this clock.

9

SDI

DI

Serial Data Input. This input provides multiple features. It selects the interface mode of the ADC as

follows:

Chain mode is selected if SDI is low during the CNV rising edge. In this mode, SDI is used as a

data input to daisy-chain the conversion results of two or more ADCs onto a single SDO line. The

digital data level on SDI is output on SDO with a delay of 18 SCK cycles.

CS mode is selected if SDI is high during the CNV rising edge. In this mode, either SDI or CNV can

enable the serial output signals when low. If SDI or CNV is low when the conversion is complete,

the busy indicator feature is enabled.

10

VIO

P

Input/Output Interface Digital Power. Nominally at the same supply as the host interface

(1.8 V, 2.5 V, 3 V, or 5 V).

VIO

10

SDI

9

SCK

8

SDO

7

CNV

6

AD7984

TOP VIEW

(Not to Scale)

REF

VDD

IN+

IN–

GND

VIO

SDI

SCK

SDO

CNV

1

2

3

4

10

9

8

7

5

6

*EXPOSED PADDLE CAN BE CONNECTED

TO GROUND.

AD7984

(EXPOSED

PAD)*