AD7989-1/AD7989-5

Data Sheet

Rev. B | Page 8 of 24

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

Figure 4. 10-Lead MSOP Pin Configuration

Figure 5. 10-Lead LFCSP Pin Configuration

Table 7. Pin Function Descriptions

Pin No.

Mnemonic

Description

1

REF

AI

Reference Input Voltage. The REF range is 2.4 V to 5.1 V. This pin is referred to the GND pin and must 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

Conversion Input. This input has multiple functions. On its leading edge, it initiates the conversions and

selects the interface mode of the device: chain mode or chip select (CS) mode. In CS mode, the SDO pin is

enabled when CNV is low. In chain mode, the data is 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 device is selected, the conversion result is shifted out by this clock.

9

SDI/CS

DI

Serial Data Input/Chip Select. This input has multiple functions. It selects the interface mode of the ADC as

follows:

Chain mode is selected if this pin is low during the CNV rising edge. In this mode, SDI/CS is a data input

that daisy-chains the conversion results of two or more ADCs onto a single SDO line. The digital data level

on SDI/CS is the output on SDO with a delay of 16 SCK cycles.

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

enable the serial output signals when low.

10

VIO

P

Input/Output Interface Digital Power. This pin is nominally at the same supply as the host interface (1.8 V,

2.5 V, 3 V, or 5 V).

EPAD

Exposed Pad. For the LFCSP, the exposed pad can be connected to GND. This connection is not required to

meet the electrical performances.

VIO

10

SDI/CS

9

SCK

8

SDO

7

CNV

6

AD7989-1/

AD7989-5

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NOTES

1. EXPOSED PAD. FOR THE LFCSP, THE

EXPOSED PAD CAN BE CONNECTED TO GND.

THIS CONNECTION IS NOT REQUIRED TO

MEET THE ELECTRICAL PERFORMANCES.

1

REF

2

VDD

3

IN+

4

IN–

5

GND

10 VIO

9SDI/CS

8SCK

7SDO

6CNV

AD7989-1/

AD7989-5

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