AD7623

Rev. 0 | Page 9 of 28

Pin No.

Mnemonic

Description

16

D7

DI/O

Bit 7 of the Parallel Port Data Output Bus.

or RDC

When SER/PAR = high, read during convert. When using serial master mode (EXT/INT = low), RDC is

used to select the read mode.

When RDC = high, the previous conversion result is read during current conversion and the period of

SCLK changes (see the Master Serial Interface section).

When RDC = low (read after convert), the current result is read after conversion.

or SDIN

Serial Data In. When using serial slave mode, (EXT/INT = high), SDIN could be used as a data input to

daisy-chain the conversion results from two or more ADCs onto a single SDOUT line. The digital data

level on SDIN is output on SDOUT with a delay of 16 SCLK periods after the initiation of the read

sequence.

17

OGND

P

Input/Output Interface Digital Power Ground.

18

OVDD

P

Input/Output Interface Digital Power. Nominally at the same supply as the supply of the host interface

(2.5 V or 3 V).

19

DVDD

P

Digital Power. Nominally at 2.5 V.

20

DGND

P

Digital Power Ground.

21

D8

DO

When SER/PAR = low, this output is used as Bit 8 of the parallel port data output bus.

or SDOUT

When SER/PAR = high, serial data output. In serial mode, this pin is used as the serial data output

synchronized to SCLK. Conversion results are stored in an on-chip register. The AD7623 provides the

conversion result, MSB first, from its internal shift register. The data format is determined by the logic

level of OB/2C.

In master mode, (EXT/INT = low). SDOUT is valid on both edges of SCLK.

In slave mode, (EXT/INT = high):

When INVSCLK = low, SDOUT is updated on SCLK rising edge and valid on the next falling edge.

When INVSCLK = high, SDOUT is updated on SCLK falling edge and valid on the next rising edge.

22

D9

DI/O

Parallel Port Data Output Bus Bit 9. When SER/PAR = low, this output is used as Bit 9 of the parallel port

data output bus.

or SCLK

Serial Clock. When SER/PAR = high, serial clock. In all serial modes, this pin is used as the serial data

clock input or output, dependent on the logic state of the EXT/INT pin. The active edge where the data

SDOUT is updated depends on the logic state of the INVSCLK pin.

23

D10

DO

When SER/PAR = low, this output is used as Bit 10 of the parallel port data output bus.

or SYNC

When SER/PAR = high, frame synchronization. In serial master mode (EXT/INT= low), this output is

used as a digital output frame synchronization for use with the internal data clock.

When a read sequence is initiated and INVSYNC = low, SYNC is driven high and remains high while

SDOUT output is valid.

When a read sequence is initiated and INVSYNC = high, SYNC is driven low and remains low while

SDOUT output is valid.

24

D11

DO

Parallel Port Data Output Bus Bit 11. When SER/PAR = low, this output is used as Bit 11 of the parallel

port data output bus.

or RDERROR

Read Error. When SER/PAR = high, read error. In serial slave mode (EXT/INT = high), this output is used

as an incomplete read error flag. If a data read is started and not completed when the current

conversion is complete, the current data is lost and RDERROR is pulsed high.

25 to 28

D[12:15]

DO

Bit 12 to Bit 15 of the Parallel Port Data Output Bus.

29

BUSY

DO

Busy Output. Transitions high when a conversion is started, and remains high until the conversion is

complete and the data is latched into the on-chip shift register. The falling edge of BUSY can be used

as a data ready clock signal.

30

DGND

P

Digital Power Ground.

31

RD

DI

Read Data. When CS and RD are both low, the interface parallel or serial output bus is enabled.

32

CS

DI

Chip Select. When CS and RD are both low, the interface parallel or serial output bus is enabled. CS is

also used to gate the external clock in slave serial mode.

33

RESET

DI

Reset Input. When high, reset the AD7623. Current conversion if any is aborted. Falling edge of RESET

enables the calibration mode indicated by pulsing BUSY high. Refer to the Digital Interface section. If

not used, this pin can be tied to DGND.

34

PD

DI

Power-Down Input. When high, power down the ADC. Power consumption is reduced and conversions

are inhibited after the current one is completed.