AD1937 datasheet(20/36 Pages) AD

20 / 36 page

AD1937

Rev. 0 | Page 20 of 36

TIME-DIVISION MULTIPLEXED (TDM) MODES

The serial ports of the AD1937 have several different TDM

serial data modes. Single-line TDM mode is the most com-

monly used configuration (see Figure 16 and Figure 17).

These figures show 8-channel configuration; other possible

options are 4- and 16-channel configurations. In Figure 16,

the eight on-chip DAC data slots are packed into one I2S

TDM stream. In this mode, both DBCLK and ABCLK are

256 fS. In Figure 17, the ADC serial port outputs one data

stream consisting of four on-chip ADCs followed by four

unused slots.

SLOT 1

LEFT 1

SLOT 2

RIGHT 1

SLOT 3

LEFT 2

SLOT 4

RIGHT 2

MSB

MSB – 1

MSB – 2

DATA

BCLK

LRCLK

SLOT 5

LEFT 3

SLOT 6

RIGHT 3

SLOT 7

LEFT 4

SLOT 8

RIGHT 4

DLRCLK

DBCLK

DSDATA

256 BCLKs

32 BCLKs

Figure 16. Single-Line TDM Mode 8-Channel DAC Configuration

SLOT 1

LEFT 1

SLOT 2

RIGHT 1

SLOT 3

LEFT 2

SLOT 4

RIGHT 2

MSB

MSB – 1

MSB – 2

DATA

BCLK

LRCLK

SLOT 5 SLOT 6 SLOT 7 SLOT 8

ALRCLK

ABCLK

ASDATA

256 BCLKs

32 BCLKs

Figure 17. Single-Line TDM Mode 8-Channel ADC Configuration

The I/O pin functions of the serial ports are defined according

to the serial mode that is selected. For a detailed description of

the function of each pin in TDM and TDM/AUX modes, see

Table 18.

The AD1937 allows systems with more than eight DAC channels

to be easily configured by the use of an auxiliary serial data port.

The TDM/AUX mode 16-channel configuration is shown in

Figure 18. In this mode, the AUX channels are the last four

slots of the TDM data stream. These slots are extracted and

output to the AUX serial port. It should be noted that due to

the high DBCLK frequency, this mode is available only in the

48 kHz/44.1 kHz/32 kHz sample rates. An 8-channel DAC

configuration cannot be TDM/AUX because there are no

extra data slots for the AUX packets; this would be single-

line TDM mode.

The AD1937 also allows system configurations with more

than four ADC channels as shown in Figure 19 (using 8 ADCs)

and Figure 20 (using 16 ADCs). Due to the high ABCLK

frequency, this mode is available only in the 48 kHz/44.1 kHz/

32 kHz sample rates.

Combining the TDM/AUX ADC and DAC modes results in

a system configuration of 8 ADCs and 12 DACs. The system,

then consists of two external stereo ADCs, two external stereo

DACs, and one AD1937. This mode is shown in Figure 21

(combined TDM/AUX DAC and ADC modes).

In the TDM/AUX mode, the frame sync (ALRCLK) triggers

the TDM word by crossing the high frequency TDM BCLK

(ABCLK) to 0, similar to the single-line TDM modes (see

Figure 16 and Figure 17). The AUX LRCLK (DLRCLK) runs at

the much slower fS of the AUX port; the AUX BCLK (DBCLK)

runs at 64 × fS. This is shown in the TDM/AUX figures (see

Figure 18 to Figure 21).

Table 18. Pin Function Changes in TDM and TDM/AUX Modes

Mnemonic

Stereo Modes

TDM Modes

TDM/AUX Modes

ASDATA1

ADC1 data out

TDM ADC data out

TDM data out

ASDATA2

ADC2 data out

TDM ADC data in

AUX DAC1 data out (to external DAC1)

DSDATA1

DAC1 data in

TDM DAC data in

TDM data in

DSDATA2

DAC2 data in

TDM DAC data out

AUX ADC1 data in (from external ADC1)

DSDATA3

DAC3 data in

TDM DAC2 data in (dual-line mode)

AUX ADC2 data in (from external ADC2)

DSDATA4

DAC4 data in

TDM DAC2 data out (dual-line mode)

AUX DAC2 data out (to external DAC2)

ALRCLK

ADC LRCLK in/out

TDM ADC frame sync in/out

TDM frame sync in/out

ABCLK

ADC BCLK in/out

TDM ADC BCLK in/out

TDM BCLK in/out

DLRCLK

DAC LRCLK in/out

TDM DAC frame sync in/out

AUX LRCLK in/out

DBCLK

DAC BCLK in/out

TDM DAC BCLK in/out

AUX BCLK in/out

AD1937 Datasheet(PDF) 20 Page - Analog Devices

AD1937 Datasheet(HTML) 20 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

Datasheet Download

Link URL