REV. 0

–8–

AD7738

PIN FUNCTION DESCRIPTION (continued)

Pin No.

Mnemonic

Pin Description

15

ADCIN(–)

ADC Negative Input. In normal circuit configuration, this pin should be connected to the MUXOUT– pin.

16

ADCIN(+)

ADC Positive Input. In normal circuit configuration, this pin should be connected to the MUXOUT+ pin.

21

REFIN(+)

Positive Terminal of the Differential Reference Input. REFIN+ voltage potential can lie any where between

22

REFIN(–)

Negative Terminal of the Differential Reference Input. REFIN– voltage potential can lie any where between

23

AGND

Ground Reference Point for Analog Circuitry

24

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 RDY function bit in the I/O Port register. In calibration mode, a falling edge

on this output indicates that calibration is complete. See more details in Digital Interface Description

section later in this data sheet.

25

DOUT

Serial Data Output with serial data being read from the output shift register on the part. This output

shift register can contain information from any AD7738 register depending on the address bits of the

Communications register.

26

DIN

Serial Data Input (Schmitt triggered) with serial data being written to the input shift register on the part.

Data from this input shift register is transferred to any AD7738 register depending on the address bits of

the Communications register.

27

Digital Supply Voltage, 3 V or 5 V Nominal

28

DGND

Ground Reference Point for Digital Circuitry