EVAL-AD1939AZ Analog Devices Inc, EVAL-AD1939AZ Datasheet - Page 15

• Manufacturer Part Number: EVAL-AD1939AZ
• Description: Eval BD FOR MULTI CHANNEL 96KHz Codec
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD1939AZ

• Main Purpose: Audio, CODEC
• Utilized Ic / Part: AD1939
• Primary Attributes: 24-Bit, 192 kHz, 4 ADCs: 107dB Dynamic Range, 8 DACs: 112dB Dynamic Range
• Secondary Attributes: Time Division Multiplexed (TDM), SPI Interface
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Embedded: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

POWER SUPPLY AND VOLTAGE REFERENCE
The AD1939 is designed for 3.3 V supplies. Separate power
supply pins are provided for the analog and digital sections.
To minimize noise pickup, these pins should be bypassed with
100 nF ceramic chip capacitors placed as close to the pins as
possible. A bulk aluminum electrolytic capacitor of at least
22 μF should also be provided on the same PC board as the
codec. For critical applications, improved performance is
obtained with separate supplies for the analog and digital sections.
If this is not possible, it is recommended that the analog and
digital supplies be isolated by means of a ferrite bead in series
with each supply. It is important that the analog supply be as
clean as possible.
The AD1939 includes a 3.3 V regulator driver that only requires
an external pass transistor and bypass capacitors to make a 5 V
to 3.3 V regulator. If the regulator driver is not used, connect
VSUPPLY, VDRIVE, and VSENSE to DGND.
All digital inputs are compatible with TTL and CMOS levels.
All outputs are driven from the 3.3 V DVDD supply and are
compatible with TTL and 3.3 V CMOS levels.
The ADC and DAC internal voltage reference (V
out on FILTR and should be bypassed as close as possible to the
chip with a parallel combination of 10 μF and 100 nF. Any
external current drawn should be limited to less than 50 μA.
The internal reference can be disabled in the PLL and Clock
Control 1 register and FILTR can be driven from an external
source. This can be used to scale the DAC output to the clipping
level of a power amplifier based on its power supply voltage.
The ADC input gain varies by the inverse ratio. The total gain
from ADC input to DAC output remains constant.
The CM pin is the internal common-mode reference. It should
be bypassed as close as possible to the chip, with a parallel
combination of 47 μF and 100 nF. This voltage can be used to
bias external op amps to the common-mode voltage of the input
and output signal pins. The output current should be limited to
less than 0.5 mA source and 2 mA sink.
SERIAL DATA PORTS—DATA FORMAT
The eight DAC channels use a common serial bit clock (DBCLK)
and a common left-right framing clock (DLRCLK) in the serial
data port. The four ADC channels use a common serial bit
clock (ABCLK) and left-right framing clock (ALRCLK) in the
serial data port. The clock signals are all synchronous with the
sample rate. The normal stereo serial modes are shown in
Figure 23.
The ADC and DAC serial data modes default to I
can also be programmed for left-justified, right-justified, and
TDM modes. The word width is 24 bits by default and can be
programmed for 16 or 20 bits. The DAC serial formats are
programmable according to the DAC Control 0 register. The
REF
2
S. The ports
) is brought
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polarity of DBCLK and DLRCLK is programmable according to
the DAC Control 1 register. The ADC serial formats and serial
clock polarity are programmable according to the ADC Control 1
register. Both DAC and ADC serial ports are programmable to
become the bus masters according to DAC Control 1 register
and ADC Control 2 register. By default, both ADC and DAC
serial ports are in the slave mode.
TIME-DIVISION MULTIPLEXED (TDM) MODES
The AD1939 serial ports also have several different TDM serial
data modes. The first and most commonly used configurations
are shown in Figure 12 and Figure 13. In Figure 12, the ADC
serial port outputs one data stream consisting of four on-chip
ADCs followed by four unused slots. In Figure 13, the eight on-
chip DAC data slots are packed into one TDM stream. In this
mode, both DBCLK and ABCLK are 256 f
LRCLK
The I/O pins 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 AUX modes, see Table 12.
The AD1939 allows systems with more than eight DAC channels
to be easily configured by the use of an auxiliary serial data port.
The DAC TDM-AUX mode is shown in Figure 14. 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 rate.
The AD1939 also allows system configurations with more than
four ADC channels as shown in Figure 15 (using 8 ADCs) and
Figure 16 (using 16 ADCs). Again, due to the high ABCLK fre-
quency, this mode is available only in the 48 kHz/44.1 kHz/32 kHz
sample rate.
LRCLK
BCLK
DATA
BCLK
DATA
32 BCLKs
32 BCLKs
SLOT 1
LEFT 1
SLOT 1
LEFT 1
RIGHT 1
RIGHT 1
SLOT 2
SLOT 2
Figure 12. ADC TDM (8-Channel I
Figure 13. DAC TDM (8-Channel I
MSB
MSB
SLOT 3
LEFT 2
SLOT 3
LEFT 2
MSB–1
MSB–1
RIGHT 2
RIGHT 2
SLOT 4
SLOT 4
256 BCLKs
256 BCLKs
MSB–2
MSB–2
SLOT 5
SLOT 5
LEFT 3
LRCLK
BCLK
DATA
LRCLK
BCLK
DATA
RIGHT 3
SLOT 6
SLOT 6
S
2
2
S Mode)
S Mode)
.
SLOT 7
SLOT 7
LEFT 4
AD1939
RIGHT 4
SLOT 8
SLOT 8