AD1937WBSTZ datasheet(24/37 Pages) AD

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AD1937

DLRCLK

DBCLK

Rev. B | Page 23 of 36

DAISY-CHAIN MODE

The AD1937 also allows a daisy-chain configuration to expand

the system to 16 DACs and 8 ADCs (see Figure 22 to Figure 26).

In this mode, the DBCLK frequency is 512 × fS. The first eight

slots of the TDM DAC data stream belong to the first AD1937

in the chain and the last eight slots belong to the second AD1937.

The second AD1937 is the device attached to the DSP TDM port.

To accommodate 16 channels at a 96 kHz sample rate, the

AD1937 can be configured into a dual-line, TDM mode as

shown in Figure 23. This mode allows a slower DBCLK than

normally required by the one-line TDM mode. The first four

channels of each TDM input belong to the first AD1937 in the

chain and the last four channels belong to the second AD1937.

The dual-line TDM mode can also be used to send data at a

192 kHz sample rate into the AD1937, as shown in Figure 24.

There are two configurations for the ADC port to work in

daisy-chain mode. The first configuration is with an ABCLK

at 256 × fS, see Figure 25. The second configuration is with an

ABCLK at 512 × fS, see Figure 26. Note that in the 512 × fS

ABCLK mode, the ADC channels occupy the first eight

slots; the second eight slots are empty. The TDM ADC data

in (ASDATA2) port of the first AD1937 must be grounded

in all modes of operation.

The I/O pins of the serial ports are defined according to the

serial mode selected. See Table 19 for a detailed description

of the function of each pin. See Figure 27 for a typical AD1937

configuration with two external stereo DACs and two external

stereo ADCs.

8 DAC CHANNELS OF THE FIRST IC IN THE CHAIN

8 UNUSED SLOTS

8 DAC CHANNELS OF THE SECOND IC IN THE CHAIN

DSDATA1 (TDM ADC DATA IN)

OF THE SECOND AD1937

DSDATA2 (TDM DAC DATA OUT)

OF THE SECOND AD1937;

THIS IS THE TDM

TO THE FIRST AD1937

DAC1L

DAC1R

DAC2L

DAC2R

DAC3L

DAC3R

DAC4L

DAC4R

DAC1L

DAC1R

DAC2L

DAC2R

DAC3L

DAC3R

DAC4L

DAC4R

DAC1L

DAC1R

DAC2L

DAC2R

DAC3L

DAC3R

DAC4L

DAC4R

32 BITS

MSB

DSP

SECOND

AD1937

FIRST

AD1937

Figure 22. Single-Line Daisy-Chain TDM Mode 16-Channel 48 kHz DAC Configuration

DLRCLK

DBCLK

8 DAC CHANNELS OF THE SECOND IC IN THE CHAIN

8 DAC CHANNELS OF THE FIRST IC IN THE CHAIN

DSDATA1

(TDM DAC DATA IN)

DAC1L

DAC1R

DAC2L

DAC2R

DAC1L

DAC1R

DAC2L

DAC2R

DSDATA3

(TDM DAC2 DATA IN)

DAC3L

DAC3R

DAC4L

DAC4R

DAC3L

DAC3R

DAC4L

DAC4R

DSDATA2

(TDM DAC DATA OUT)

DAC1L

DAC1R

DAC2L

DAC2R

DSDATA4

(TDM DAC2 DATA OUT)

DAC3L

DAC3R

DAC4L

DAC4R

32 BITS

DSP

SECOND

AD1937

FIRST

AD1937

MSB

Figure 23. Dual-Line Daisy-Chain TDM Mode16-Channel 96 kHz DAC Configuration

AD1937WBSTZ Datasheet(PDF) 24 Page - Analog Devices

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