AD7682/AD7689

Rev. 0 | Page 9 of 28

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

PIN 1

INDICATOR

1

VDD

2

REF

NC = NO CONNECT

3

REFIN

4

GND

5

GND

13 SCK

14 SDO

15 VIO

12 DIN

11 CNV

TOP VIEW

(Not to Scale)

AD7682

Figure 4. AD7682 20-Lead LFCSP (QFN) Pin Configuration

PIN 1

INDICATOR

1

VDD

2

REF

3

REFIN

4

GND

5

GND

13 SCK

14 SDO

15 VIO

12 DIN

11 CNV

TOP VIEW

(Not to Scale)

AD7689

Figure 5. AD7689 20-Lead LFCSP (QFN) Pin Configuration

Table 6. Pin Function Descriptions

Pin

No.

AD7682

Mnemonic

AD7689

Mnemonic

Type1

Description

1, 20

VDD

VDD

P

Power Supply. Nominally 2.5 V to 5.5 V when using an external reference and decoupled

with 10 μF and 100 nF capacitors.

When using the internal reference for 2.5 V output, the minimum should be 2.7 V.

When using the internal reference for 4.096 V output, the minimum should be 4.5 V.

2

REF

REF

AI/O

Reference Input/Output. See the Voltage Reference Output/Input section.

When the internal reference is enabled, this pin produces a selectable system

reference = 2.5 V or 4.096 V.

When the internal reference is disabled and the buffer is enabled, REF produces a

buffered version of the voltage present on the REFIN pin (VDD – 0.3 V maximum) useful

when using low cost, low power references.

For improved drift performance, connect a precision reference to REF (0.5 V to VDD).

For any reference method, this pin needs decoupling with an external 10 μF capacitor

connected as close to REF as possible. See the Reference Decoupling section.

3

REFIN

REFIN

AI/O

Internal Reference Output/Reference Buffer Input. See the Voltage Reference

Output/Input section.

When using the internal reference, the internal unbuffered reference voltage is present

and needs decoupling with a 0.1μF capacitor.

When using the internal reference buffer, apply a source between 0.5 V and 4.096 V that

is buffered to the REF pin as described above.

4, 5

GND

GND

P

Power Supply Ground.

6

NC

IN4

AI

AD7682: No connection.

AD7689: Analog Input Channel 4.

7

IN2

IN5

AI

AD7682: Analog Input Channel 2.

AD7689: Analog Input Channel 5.

8

NC

IN6

AI

AD7682: No connection.

AD7689: Analog Input Channel 6.

9

IN3

IN7

AI

AD7682: Analog Input Channel 3.

AD7689: Analog Input Channel 7.

10

COM

COM

AI

Common Channel Input. All channels [3:0] or [7:0] can be referenced to a common mode

11

CNV

CNV

DI

Convert Input. On the rising edge, CNV initiates the conversion. During conversion, if

CNV is held high, the busy indictor is enabled.

12

DIN

DIN

DI

Data Input. This input is used for writing to the 14-bit configuration register. The

configuration register can be written to during and after conversion.

13

SCK

SCK

DI

Serial Data Clock Input. This input is used to clock out the data on ADO and clock in data

on DIN in an MSB first fashion.