AD7691

Data Sheet

Rev. E | Page 8 of 28

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

Figure 5. 10-Lead MSOP Pin Configuration

Figure 6. 10-Lead LFCSP Pin Configuration

Table 8. Pin Function Descriptions

Pin No.

Mnemonic

Description

1

REF

AI

Reference Input Voltage. The REF range is from 0.5 V to VDD. It is referred to the GND pin.

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

2

VDD

P

Power Supply.

3

IN+

AI

4

IN−

AI

5

GND

P

Power Supply Ground.

6

CNV

DI

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

selects the interface mode of the part, either chain or CS mode. In CS mode, it enables the SDO pin when

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, and 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).

EPAD

Exposed Pad. The exposed pad is not connected internally. For increased reliability of the solder joints, it is

recommended that the pad be soldered to the ground plane.

VIO

10

SDI

9

SCK

8

SDO

7

CNV

6

AD7691

TOP VIEW

(Not to Scale)

1

REF

2

VDD

3

IN+

4

IN–

5

GND

10 VIO

9SDI

8SCK

7SDO

6 CNV

TOP VIEW

(Not to Scale)

AD7691

NOTES

1. THE EXPOSED PAD IS NOT CONNECTED

INTERNALLY. FOR INCREASED RELIABILITY OF

THE SOLDER JOINTS, IT IS RECOMMENDED THAT

THE PAD BE SOLDERED TO THE GROUND PLANE.