Data Sheet

AD7634

Rev. B | Page 9 of 32

Pin No.

Mnemonic

Type1

Description

8

D1/A0

DI/O

When MODE[1:0] = 0, this pin is Bit 1 of the parallel port data output bus. In all other modes, this

input pin controls the form in which data is output as shown in Table 7.

9

D2/A1

DI/O

When MODE[1:0] = 0, this pin is Bit 2 of the parallel port data output bus.

When MODE[1:0] = 1 or 2, this input pin controls the form in which data is output as shown in Table 7.

10

D3

DO

When MODE[1:0] = 0, 1, or 2, this output is used as Bit 3 of the parallel port data output bus.

This pin is always an output, regardless of the interface mode.

11, 12

D[4:5] or

DI/O

When MODE[1:0] = 0, 1, or 2, these pins are Bit 4 and Bit 5 of the parallel port data output bus.

DIVSCLK[0:1]

When MODE[1:0] = 3, serial data clock division selection. When using serial master read after convert

mode (EXT/INT = low, RDC/SDIN = low), these inputs can be used to slow down the internally

generated serial clock that clocks the data output. In other serial modes, these pins are high

impedance outputs.

13

D6 or

DO/I

When MODE[1:0] = 0, 1, or 2, this output is used as Bit 6 of the parallel port data output bus.

EXT/INT

When MODE[1:0] = 3, Serial Data Clock Source Select. In serial mode, this input is used to select

the internally generated (master) or external (slave) serial data clock for the AD7634 output data.

When EXT/INT = low (master mode), the internal serial data clock is selected on SDCLK output.

When EXT/INT = high (slave mode), the output data is synchronized to an external clock signal (gated by CS)

connected to the SDCLK input.

14

D7 or

DI/O

When MODE[1:0] = 0, 1, or 2, this output is used as Bit 7 of the parallel port data output bus.

INVSYNC

When MODE[1:0] = 3, Serial Data Invert Sync Select. In serial master mode (MODE[1:0] = 3,

EXT/INT = low), this input is used to select the active state of the SYNC signal.

When INVSYNC = low, SYNC is active high.

When INVSYNC = high, SYNC is active low.

15

D8 or

DI/O

When MODE[1:0] = 0, 1, or 2, this output is used as Bit 8 of the parallel port data output bus.

INVSCLK

When MODE[1:0] = 3, Invert SDCLK/SCCLK Select. This input is used to invert both SDCLK and SCCLK.

When INVSCLK = low, the rising edge of SDCLK/SCCLK are used.

When INVSCLK = high, the falling edge of SDCLK/SCCLK are used.

16

D9 or

DI/O

When MODE[1:0] = 0, 1, or 2, this output is used as Bit 9 of the parallel port data output bus.

RDC or

When MODE[1:0] = 3, Serial Data Read During Convert. In serial master mode (MODE[1:0] = 3,

EXT/INT = low), RDC is used to select the read mode. See the Master Serial Interface section.

When RDC = low, the current result is read after conversion. Note the maximum throughput is not

attainable in this mode.

When RDC = high, the previous conversion result is read during the current conversion.

SDIN

When MODE[1:0] = 3, Serial Data In. In serial slave mode (MODE[1:0] = 3, EXT/INT = high), SDIN can 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 SDCLK periods after the initiation

of the read sequence.

17

OGND

P

Input/Output Interface Digital Power Ground. Ground reference point for digital outputs. Should be

connected to the system digital ground ideally at the same potential as AGND and DGND.

18

OVDD

P

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

2.5 V, 3 V, or 5 V and decoupled with 10 μF and 100 nF capacitors.

19

DVDD

P

Digital Power. Nominally at 4.75 V to 5.25 V and decoupled with 10 μF and 100 nF capacitors. Can be

supplied from AVDD.

20

DGND

P

Digital Power Ground. Ground reference point for digital outputs. Should be connected to system

digital ground ideally at the same potential as AGND and OGND.

21

D10 or

DI/O

When MODE[1:0] = 0, 1, or 2, this output is used as Bit 10 of the parallel port data output bus.

SDOUT

When MODE[1:0] = 3, Serial Data Output. In all serial modes, this pin is used as the serial data output

synchronized to SDCLK. Conversion results are stored in an on-chip register. The AD7634 provides the

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

level of OB/2C.

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

When EXT/INT = high (slave mode):

When INVSCLK = low, SDOUT is updated on SDCLK rising edge.

When INVSCLK = high, SDOUT is updated on SDCLK falling edge.