AD1843JS Analog Devices Inc, AD1843JS Datasheet - Page 20

• Manufacturer Part Number: AD1843JS
• Description: IC CODEC STEREO 5V 16BIT 80PQFP
• Manufacturer: Analog Devices Inc
• Type: Stereo Audior

Specifications of AD1843JS

• Rohs Status: RoHS non-compliant
• Data Interface: Serial
• Resolution (bits): 16 b
• Number Of Adcs / Dacs: 1 / 2
• Sigma Delta: Yes
• S/n Ratio, Adcs / Dacs (db) Typ: 92 / 86
• Dynamic Range, Adcs / Dacs (db) Typ: 85 / 80
• Voltage - Supply, Analog: 4.75 V ~ 5.25 V
• Voltage - Supply, Digital: 2.85 V ~ 5.25 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 80-MQFP, 80-PQFP

AD1843
produced by an AD1843 serving as bus master, an AD1843
serving as bus slave does not actually require these frame sizes.
When FRS is set to “1,” a slave will operate correctly with any
number or fraction of slots, provided there are enough slots for
it to complete its necessary communication (see below). When
FRS is reset to “0,” a slave can also operate correctly with a
wide range in the number of slots per frame, however it will au-
tomatically retake ownership of the serial interface bus 16 slots
after it is first given ownership of the bus in a frame.
The nominal minimum number of slots when the AD1843 is
configured in slave mode is six. The codec must be supplied
with at least 6
edges); SCLK may be gated (i.e., no need to be continuous)
between valid slots.
While SDFS marks the beginning of frames, AD1843 bus own-
ership during a frame is controlled by the TSI (Time Slot In)
and TSO (Time Slot Out) pins. When bus slave, a level HI on
TSI grants the AD1843 bus ownership beginning with the next
SCLK period. The TSI pin is monitored only when an AD1843
does not already own the bus; once an AD1843 is given owner-
ship of the bus, the level on TSI is ignored until one SCLK
period before bus ownership is relinquished. Bus ownership will
last for six slots. Coincident with the final SCLK period of the
final slot owned, the AD1843 asserts TSO HI. This allows
chaining of AD1843s onto a common serial bus by connecting
the TSO pin of one AD1843 to the TSI pin on the next later
AD1843 in a chain. In single codec systems where the
SoundComm is configured as bus slave, connect the AD1843
SDFS and TSI signals together. When an AD1843 is bus mas-
ter, its function is identical to that just described for the slave,
except a bus master always owns the first six slots and its TSI
pin is ignored (but should be tied LO).
Whenever an AD1843 does not own the bus, its SDO pin will
be three-stated and its SDI pin is ignored. Figures 7 through 10
illustrate the signal, slot, sample and frame relationships for the
four basic operating modes of the AD1843 serial interface.
The AD1843 requires slots of communication each time it takes
ownership of the serial bus. The first slot is used for a Control
Word input and a Status Word output. The second slot is used
32 Slot Mode (FRS Reset to “0”)
Slot
0 & 16
1 & 17
2 & 18
3 & 19
4 & 20
5 & 21
16 Slot Mode (FRS Set to “1”)
Slot
0
1
2
3
4
5
16 = 96 SCLK periods (both rising and falling
SDI Pin
Control Word Input
Control Register Data Input
Playback Data Input—DAC1 Left
Playback Data Input—DAC1 Right
Playback Data Input—DAC2 Left
Playback Data Input—DAC2 Right
SDI Pin
Control Word Input
Control Register Data Input
Playback Data Input—DAC1 Left
Playback Data Input—DAC1 Right
Playback Data Input—DAC2 Left
Playback Data Input—DAC2 Right
Table II. AD1843 Slot Assignment
–20–
for Control Register write data input and read data output. The
remaining slots are used for playback (DAC) data input and
capture (ADC) data output, where each channel has an assigned
slot. Table II and Figure 11 illustrate these slot assignments.
Since the conversion channels of the AD1843 can be pro-
grammed to run at different sample rates, a communication
mechanism indicates when playback channels request data,
when playback data is actually sent to the AD1843, and when
transmission of capture data from the AD1843 becomes neces-
sary. This is facilitated by the Control and Status Words lo-
cated in the first slot. The Control Word indicates which slots
in the current frame contain valid playback data. The Status
Word indicates if playback data can be sent to the AD1843 dur-
ing the next frame, and which slots in the current frame contain
valid capture data. See the descriptions of the Control Word
and the Status Word below for additional detail.
Four word FIFO buffers are used on the inputs of each of the
DACs to allow data to be transferred in small bursts. This re-
duces the required response time to playback data requests, and
also buffers differences between the frame sync rate and the
channel sample rate. The Status Word indicates that playback
data can be sent if there is any room in the buffers, thus tending
to keep the input buffers full. Underrun flags are available in
Control Register 1, which indicate if an input buffer ran out of
data. If an underrun occurs, a zero is used in place of the un-
available data. To ensure underruns do not occur, playback data
must be sent to the AD1843 within two sample periods after the
status word indicates that the DAC FIFO is not full.
Note that the DAC Not Full status bits (DA2RQ and DA1RQ
in the Status Word Output) are updated immediately (i.e., in
the same frame as a valid write to the DAC FIFOs). If the DAC
Input Valid Flags (DA2V and DA1V in the Control Word
Input) are set (i.e., DAC data is valid) and only one location in
the DAC1 and DAC2 input FIFOs is available, then the
DA2RQ and DA1RQ status bits will reflect this valid write, and
will be reset to “0.” This is possible because the DA2V and
DA1V bits are in the most significant bits of the Control Word
and the DA2RQ and DA1RQ bits are in the least significant bits
of the Status Word, and the AD1843 uses this intervening time
SDO Pin
Status Word Output
Control Register Data Output
Capture Data Output—ADC Left
Capture Data Output—ADC Right
Reserved (Unused)
Reserved (Unused)
SDO Pin
Status Word Output
Control Register Data Output
Capture Data Output—ADC Left
Capture Data Output—ADC Right
Reserved (Unused)
Reserved (Unused)
REV. 0