Data Sheet

AD1939

Rev. E | Page 29 of 32

ADDITIONAL MODES

The AD1939 offers several additional modes for board level

design enhancements. To reduce the EMI in board level design,

serial data can be transmitted without an explicit BCLK. See

Figure 27 for an example of a DAC TDM data transmission

mode that does not require high speed DBCLK. This configura-

tion is applicable when the AD1939 master clock is generated

by the PLL with the DLRCLK as the PLL reference frequency.

To relax the requirement for the setup time of the AD1939 in

cases of high speed TDM data transmission, the AD1939 can

latch in the data using the falling edge of DBCLK. This effec-

tively dedicates the entire BCLK period to the setup time. This

mode is useful in cases where the source has a large delay time

in the serial data driver. Figure 28 shows this pipeline mode of

data transmission.

Both the BCLK-less and pipeline modes are available on the

ADC serial data port.

DLRCLK

INTERNAL

DBCLK

DSDATAx

DLRCLK

INTERNAL

DBCLK

TDM-DSDATAx

32 BITS

Figure 27. Serial DAC Data Transmission in TDM Format Without DBCLK

(Applicable Only If PLL Locks to DLRCLK, This Mode Is Also Available in the ADC Serial Data Port)

DLRCLK

DBCLK

DSDATAx

DATA MUST BE VALID

AT THIS BCLK EDGE

MSB

(Applicable in Stereo and TDM, Useful for High Frequency TDM Transmission,

This Mode Is Also Available in the ADC Serial Data Port)