REV. 0

AD7719

–9–

PIN CONFIGURATION

14

13

12

11

10

17

16

15

19

18

20

28

27

26

25

24

23

22

21

9

8

1

2

3

4

7

6

5

TOP VIEW

(Not to Scale)

AD7719

IOUT1

DGND

XTAL2

XTAL1

IOUT2

AGND

RDY

DOUT

DIN

REFIN1(–)

REFIN1(+)

AIN1

AIN2

AIN3

AIN4

RESET

SCLK

CS

AIN5

AIN6

REFIN2

P4

P1/SW1

P3

P2/SW2

PWRGND

The serial interface can be reset by exercising the

RESET input

on the part. It can also be reset by writing a series of 1s on the

DIN input. If a Logic 1 is written to the AD7719 DIN line for

at least 32 serial clock cycles the serial interface is reset. This

ensures that in 3-wire systems, if the interface gets lost either via

a software error or by some glitch in the system, it can be reset

back to a known state. This state returns the interface to where

the AD7719 is expecting a write operation to its Communica-

tions Register. This operation resets the contents of all registers to

their power-on reset values.

Some microprocessor or microcontroller serial interfaces have a

single serial data line. In this case, it is possible to connect the

AD7719’s DATA OUT and DATA IN lines together and connect

them to the single data line of the processor. A 10 k

Ω pull-up

resistor should be used on this single data line. In this case, if

the interface gets lost, because the read and write operations

share the same line the procedure to reset it back to a known

state is somewhat different than previously described. It requires

a read operation of 24 serial clocks followed by a write operation

where a Logic 1 is written for at least 32 serial clock cycles to

ensure that the serial interface is back into a known state.

PIN FUNCTION DESCRIPTIONS

Pin No.

Mnemonic

Function

1

IOUT1

Output for Internal 200

µA Excitation Current Source. Either current source IEXC1 or IEXC2 or

both can be switched to this output.

2

IOUT2

Output for Internal 200

µA Excitation Current Source. Either IEXC1 or IEXC2 current source or

both can be switched to this output.

Analog Supply Voltage.

4

AGND

Analog Ground.

5

REFIN1(–)

Negative Reference Input for Main ADC Channel. This reference input can lie anywhere between

6

REFIN1(+)

AGND + 1 V. The nominal reference voltage (REFIN1(+) – REFIN1(–)) is 2.5 V, but the part is

7

AIN1

Analog Input. AIN1 is dedicated to the main channel.

8

AIN2

Analog Input. AIN2 is dedicated to the main channel.

9

AIN3

Analog Input. AIN3 can be multiplexed to either the main or auxiliary channel

10

AIN4

Analog Input. AIN4 can be multiplexed to either the main or auxiliary channel.

11

AIN5

Analog Input. AIN5 is dedicated to the auxiliary channel and is referenced to AIN6 or AGND

12

AIN6

Analog Input. AIN6 is dedicated to the auxiliary channel. It forms a differential input pair with AIN5

in fully differential input mode or is referenced to AGND in pseudo-differential mode.

13

REFIN2

Single-Ended Reference Input for Auxiliary Channel. The nominal input reference is 2.5 V. The

14

P4

15

P3