Datasheet

AD1854
–7–REV. A
MSB–2MSB–1 LSB+2 LSB+1 LSB MSB–2MSB–1MSB LSB+2 LSB+1 LSB MSB–1MSB
L/RCLK
INPUT
BCLK
INPUT
SDATA
INPUT
LEFT CHANNEL
RIGHT CHANNEL
MSB
Figure 3. Left-Justified Mode
L/RCLK
INPUT
LEFT CHANNEL
RIGHT CHANNEL
BCLK
INPUT
SDATA
INPUT
LSB MSB–1 MSB–2 LSB+2 LSB+1 LSB MSB MSB–1 MSB–2 LSB+2 LSB+1 LSB MSB MSB–1MSB
Figure 4. 32 × F
S
Packed Mode
D15
D14
D0
t
CHD
t
CCH
t
CSU
t
CCL
t
CLL
t
CLH
CDATA
CCLK
CLATCH
t
CCP
Figure 5. Serial Control Port Timing
Serial Control Port
The AD1854 serial control port is SPI-compatible. SPI (Serial
Peripheral Interface) is an industry standard serial port protocol.
The write-only serial control port gives the user access to: select
input mode, soft power-down control, soft de-emphasis, channel-
specific attenuation and mute (both channels at once). The
AD1854 serial control port consists of three signals, control
clock CCLK (Pin 4), control data CDATA (Pin 5), and control
latch CLATCH (Pin 3). The control data input must be valid
on the control clock rising edge, and the control clock must make a
LO to HI transition when there is valid data. The control latch
must make a LO-to-HI transition after the LSB has been clocked
into the AD1854, while the control clock is inactive. The timing
relation between these signals is shown in Figure 5. The control
bits are assigned as in Table IV.
Table III. Digital Timing
Min Unit
t
CCH
CCLK HI Pulsewidth 40 (Burst Mode) ns
t
CCL
CCLK LO Pulsewidth 40 (Burst Mode) ns
t
CCP
CCLK Period 80 (Burst Mode) ns
t
CSU
CDATA Setup Time 10 ns
t
CHD
CDATA Hold Time 10 ns
t
CLL
CLATCH LO Pulsewidth 10 ns
t
CLH
CLATCH HI Pulsewidth 130 (Burst Mode) ns
The serial control port is byte oriented. The data is MSB first,
and is unsigned. There is one control register for the left
channel or the right channel, as distinguished by Bit Data 10.
For power-up and reset, the default settings are: Data 11 the
mute control bit, reset default state is LO, which is the normal
(nonmuted) setting. Data 10 is LO, the Volume 9 through
Volume 0 control bits have a reset default value of 11 1111 1111,
which is an attenuation of 0.0 dB (i.e., full scale, no attenuation).
The intent with these reset defaults is to enable AD1854 applica-
tions without requiring the use of the serial control port. For those
users who do not use the serial control port, it is still possible to
mute the AD1854 output by using the MUTE (Pin 23) signal.
Note that the serial control port timing is asynchronous to the
serial data port timing. Changes made to the attenuator level
will be updated on the next edge of the L/RCLK after the
CLATCH write pulse as shown in Figure 8.
The SPI port can be used in either of two modes, Burst Mode,
or Continuous CCLK Mode, as described below.
Continuous CCLK Mode
In this mode, the maximum CCLK frequency is 3 MHz. The
CCLK can run continuously between transactions. Please note
that the LO-to-HI transition of the CLATCH with respect to
the rising edge of CCLK must be at least 130 ns, as shown in
Figure 6.
Table IV. Serial Control Bit Definitions
MSB LSB
Data 15 Data 14 Data 13 Data 12 Data 11 Data 10 Data 9 Data 8 Data 7 Data 6 Data 5 Data 4 Data 3 Data 2 Data 1 Data 0
IDPM1 IDPM0 Soft Soft 1/Mute 1/Right Volume Volume Volume Volume Volume Volume Volume Volume Volume Volume
Input Input Power- De- 0/Normal 0/Left Control Control Control Control Control Control Control Control Control Control
Mode1 Mode0 Down Emphasis (Nonmute) Data Data Data Data Data Data Data Data Data Data
Select Select