Datasheet

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
AV
DD
and AGND. In normal circuit configuration, this pin should be connected to a 2.5 V reference voltage.
22 REFIN(–) Negative Terminal of the Differential Reference Input. REFIN– voltage potential can lie any where between
AV
DD
and AGND. In normal circuit configuration, this pin should be connected to a 0 V reference voltage.
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 DV
DD
Digital Supply Voltage, 3 V or 5 V Nominal
28 DGND Ground Reference Point for Digital Circuitry