AD1838A Analog Devices, AD1838A Datasheet - Page 13

• Manufacturer Part Number: AD1838A
• Description: 2 ADC, 6 DAC 96 Khz, 24-Bit Sigma Delta Codec
• Manufacturer: Analog Devices

The DAC serial data input mode defaults to I
Bits 5, 6, and 7 in DAC Control Register 1, the mode can be
changed to RJ, DSP, LJ, or Packed Mode 256. The word width
defaults to 24 bits but can be changed by reprogramming
Bits 3 and 4 in DAC Control Register 1.
Packed Modes
The AD1838A has a packed mode that allows a DSP or other
controller to write to all DACs and read all ADCs using one
input data pin and one output data pin. Packed Mode 256
refers to the number of BCLKs in each frame. The LRCLK
is low while data from a left channel DAC or ADC is on the
data pin, and high while data from a right channel DAC or
ADC is on the data pin. DAC data is applied on the DSDATA1
pin, and ADC data is available on the ASDATA pin. Figures 7
to 10 show the timing for the packed mode. Packed mode is
available for 48 kHz and 96 kHz.
REV. A
LRCLK
SDATA
LRCLK
SDATA
LRCLK
SDATA
LRCLK
SDATA
BCLK
BCLK
BCLK
BCLK
NOTES
1. DSP MODE DOES NOT IDENTIFY CHANNEL.
2. LRCLK NORMALLY OPERATES AT
3. BCLK FREQUENCY IS NORMALLY 64
MSB
MSB
MSB
MSB
LEFT CHANNEL
LEFT CHANNEL
LEFT CHANNEL
f
S
RIGHT-JUSTIFIED MODE—SELECT NUMBER OF BITS PER CHANNEL
EXCEPT FOR DSP MODE, WHICH IS 2
LRCLK BUT MAY BE OPERATED IN BURST MODE.
LEFT-JUSTIFIED MODE—16 BITS TO 24 BITS PER CHANNEL
2
LSB
S. By changing
DSP MODE—16 BITS TO 24 BITS PER CHANNEL
I
2
S MODE—16 BITS TO 24 BITS PER CHANNEL
Figure 4. Stereo Serial Modes
LSB
LSB
LSB
1/
–13–
f
S
Auxiliary (TDM) Mode
A special auxiliary mode is provided to allow three external
stereo ADCs and one external stereo DAC to be interfaced to
the AD1838A to provide 8-in/8-out operation. In addition, this
mode supports glueless interface to a single SHARC DSP serial
port, allowing a SHARC DSP to access all eight channels of
analog I/O. In this special mode, many pins are redefined; see
Table IV for a list of redefined pins. The auxiliary and the TDM
interfaces are independently configurable to operate as masters
or slaves. When the auxiliary interface is set as a master, by
programming the Auxiliary Mode Bit in ADC Control Register 2,
the AUXLRCLK and AUXBCLK are generated by the
AD1838A. When the auxiliary interface is set as a slave, the
AUXLRCLK and AUXBCLK need to be generated by an exter-
nal ADC, as shown in Figure 13. The TDM interface can be set
to operate as a master or slave by connecting the M/S pin to
DGND or ODVDD, respectively. In master mode, the FSTDM
and BCLK signals are outputs generated by the AD1838A. In
slave mode, the FSTDM and BCLK are inputs and should be
generated by the SHARC. Both 48 kHz and 96 kHz operations
are available (based on a 12.288 MHz or 24.576 MHz MCLK)
in this mode.
MSB
f
S.
MSB
MSB
MSB
RIGHT CHANNEL
RIGHT CHANNEL
RIGHT CHANNEL
LSB
LSB
LSB
AD1838A
LSB