AD1934_13 datasheet(13/28 Pages) AD

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Data Sheet

AD1934

Rev. D | Page 13 of 28

SERIAL CONTROL PORT

The AD1934 has an SPI control port that permits programming

and reading back of the internal control registers for the ADCs,

DACs, and clock system. A standalone mode is also available

for operation without serial control; standalone is configured

at reset by connecting CIN, CCLK, and CLATCH to ground.

In standalone mode, all registers are set to default, except the

internal MCLK enable, which is set to 1. The ADC ABCLK and

ALRCLK clock ports are set to master/slave by the connecting

the COUT pin to either DVDD or ground. Standalone mode

only supports stereo mode with an I2S data format and 256 fS

MCLK rate. Refer to Table 11 for details. If CIN, CCLK, and

CLATCH are not grounded, the AD1934 SPI port is active. It

is recommended to use a weak pull-up resistor on CLATCH in

applications that have a microcontroller. This pull-up resistor

ensures that the AD1934 recognizes the presence of a micro-

controller.

The SPI control port of the AD1934 is a 4-wire serial control

port. The format is similar to the Motorola SPI format except

the input data-word is 24 bits wide. The serial bit clock and

latch can be completely asynchronous to the sample rate of the

DACs. Figure 9 shows the format of the SPI signal. The first

byte is a global address with a read/write bit. For the AD1934,

the address is 0x04, shifted left 1 bit due to the R/W bit. The

second byte is the AD1934 register address and the third byte

is the data.

Table 11. SPI vs. Standalone Mode Configuration

DAC Control

COUT

CIN

CLATCH

CCLK

SPI

OUT

1 (Pull-Up)

Standalone

D22

D23

CLATCH

CCLK

CIN

COUT

tCCH tCCL

tCDS tCDH

tCLS

tCCP

tCLH

tCOTS

tCOD

tCOE

Figure 9. Format of SPI Signal

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