Datasheet
REV. 0
AD7708/AD7718
–13–
Pin No Mnemonic Function
21 CS Chip Select Input. This is an active low logic input used to select the AD7708/AD7718. CS can
be used to select the AD7708/AD7718 in systems with more than one device on the serial bus or
as a frame synchronization signal in communicating with the device. CS can be hardwired low,
allowing the AD7708/AD7718 to be operated in 3-wire mode with SCLK, DIN, and DOUT
used to interface with the device.
22 RDY RDY is a logic low status output from the AD7708/AD7718. RDY is low when valid data exists
in the data register for the selected channel. This output returns high on completion of a read
operation from the data register. If data is not read, RDY will return high prior to the next update
indicating to the user that a read operation should not be initiated. The RDY pin also returns
low following the completion of a calibration cycle. RDY does not return high after a calibration
until the mode bits are written to enabling a new conversion or calibration.
23 DOUT Serial data output with serial data being read from the output shift register of the ADC. The output
shift register can contain data from any of the on-chip data, calibration or control registers.
24 DIN Serial Data Input with serial data being written to the input shift register on the AD7708/AD7718
Data in this shift register is transferred to the calibration or control registers within the ADC
depending on the selection bits of the Communications register.
25 DGND Ground Reference Point for the Digital Circuitry.
26 DV
DD
Digital Supply Voltage, 3 V or 5 V Nominal.
27 XTAL2 Output from the 32 kHz Crystal Oscillator or Resonator Inverter.
28 XTAL1 Input to the 32 kHz Crystal Oscillator or Resonator Inverter.
PIN CONFIGURATION
14
13
12
11
17
16
15
20
19
18
10
9
8
1
2
3
4
7
6
5
TOP VIEW
(Not to Scale)
28
27
26
25
24
23
22
21
AD7708/
AD7718
AIN7
DGND
DV
DD
XTAL2
XTAL1
AIN8
AV
DD
AGND
RDY
DOUT
DIN
REFIN1(–)
REFIN1(+)
AIN1
AIN2
AIN3
AIN4
RESET
SCLK
CS
AIN5
AINCOM
REFIN2(+)/AIN9
REFIN2(–)/AIN10
P1
AIN6
P2
AGND