AD7739

Rev. 0 | Page 13 of 32

Pin No.

Mnemonic

Description

8

SYNC/P1

SYNC/Digital Input/Digital Output. The pin direction is determined by the P1 DIR bit;

the digital value can be read/written as the P1 bit in the I/O port register. When the SYNC

bit in the I/O port register is set to 1, then the SYNC/P1 pin can be used to synchronize

the AD7739 modulator and digital filter with other devices in the system. The digital

voltage is referenced to the analog supplies. When configured as an input, the pin should

be tied high or low.

9–16

AIN0–AIN7

Analog Inputs.

17

REFIN(+)

Positive Terminal of the Differential Reference Input. REFIN(+) voltage potential can lie

connected to a 2.5 V reference voltage.

18

REFIN(–)

Negative Terminal of the Differential Reference Input. REFIN(–) voltage potential can lie

connected to a 0 V reference voltage.

19

AGND

Ground Reference Point for Analog Circuitry.

20

RDY

Logic Output. Used as a status output in both conversion mode and calibration mode. In

conversion mode, a falling edge on this output indicates that either any channel or all

channels have unread data available, according to the RDYFN bit in the I/O port register.

In calibration mode, a falling edge on this output indicates that calibration is complete

(see the Digital Interface Description section for details).

21

DOUT

Serial Data Output. Serial data is read from the output shift register on the part. This

output shift register can contain information from any AD7739 register, depending on

the address bits of the communications register.

22

DIN

Serial Data Input (Schmitt Triggered). Serial data is written to the input shift register on

the part. Data from this input shift register is transferred to any AD7739 register,

depending on the address bits of the communications register.

23

Digital Supply Voltage, 3 V or 5 V Nominal.

24

DGND

Ground Reference Point for Digital Circuitry.