PCM1712 Burr-Brown Corporation, PCM1712 Datasheet - Page 10

• Manufacturer Part Number: PCM1712
• Description: DIGITAL-TO-ANALOG CONVERTER
• Manufacturer: Burr-Brown Corporation

FUNCTIONAL DESCRIPTION
PCM1712 has several built-in functions including digital
attenuation, digital de-emphasis and soft mute. These func-
tions are software controlled. PCM1712 can be operated in
two different modes, Serial or Parallel. Serial Mode is a
three-wire interface using pin 26 (MD), pin 27 (MC), and
pin 28 (ML). Data on these pins are used to control de-
emphasis modes, mute, double-speed dubbing, input resolu-
tion and input formats. PCM1712 can also be operated in
parallel mode, where static control signals are used on pins
26 (DM1), pin 27 (DM2), and pin 28 (DSD). Operation of
both of these modes are covered in detail in the next
sections.
CAUTION: Mode control signals operate on level triggered
logic. The minimum timing conditions detailed in Figures 4
and 5 MUST be observed.
TABLE III. Serial and Parallel Mode are Selectable by
MODE CONTROL: SELECTABLE FUNCTIONS
TABLE IV. Selectable Functions in Serial Mode and
Table IV indicates which functions are selectable within the
user’s chosen mode. All of the functions shown are select-
able within the serial mode, but only de-emphasis control,
mute and double-speed dubbing may be selected when using
PCM1712 in the parallel mode.
PARALLEL-MODE: DE-EMPHASIS CONTROL
(PIN 24 [MODE] = L)
In the parallel mode, de-emphasis conditions are controlled
by the logic levels on pin 26 (DM1) and pin 27 (DM2). For
PCM1712, de-emphasis can operate at 32kHz, 44.1kHz,
48kHz, or disabled.
MODE CONTROL: SERIAL/PARALLEL SELECTION
TABLE V. De-emphasis (Pins 26 and 27).
FUNCTION
Input Data Format Selection
Input LRCI Polarity Selection
De-emphasis Control
Mute
Attenuation
Double-Speed Dubbing
NOTE: 0: Selectable, X: Not Selectable.
DM1 (Pin 26)
MODE = H
MODE = L
H
H
L
L
MODE Pin (Pin 24).
Parallel Mode.
®
PCM1712
DM2 (Pin 27)
SERIAL MODE
(MODE = H)
H
H
L
L
0
0
0
0
0
0
Serial Mode
Parallel Mode
X (Normal Mode Fixed)
PARALLEL MODE
(MODE = L)
De-emphasis
44.1kHz
32kHz
48kHz
X
X
OFF
0
0
0
10
PARALLEL-MODE: DOUBLE-SPEED DUBBING
CONTROL (PIN 24 [MODE] = L)
TABLE VI. DSD (Pin 28).
In the parallel mode, double-speed dubbing can be enabled
by holding pin 28 (DSD) at logic “low”.
SERIAL MODE CONTROL
In order to use all of PCM1712’s functionality, the serial
mode control should be used. PCM1712 must be addressed
three separate times to set all of the various registers and
flags that control these functions.
Table VII together with Figure 6 details the control of the
PCM1712 in the serial mode. Internal latches are used to
hold this serial data until the PCM1712 is enabled to use the
data. The serial mode is used by applying clocked data to the
following pins:
DIGITAL ATTENUATION
One of the functions which can be implemented through use
of the serial mode control is attenuation. This function
allows the user to control the level of the output, indepen-
dent of the input level set by the actual input data supplied
to the DAC.
Referring to Figure 5, when the first data bit (B0) on MD
(pin 26) is low, the attenuation function is enabled. The next
seven bits (B1 - B6) define a binary value, ATT_DATA, that
indicates the desired level of attenuation. The attenuation
level is given by:
When all 7 bits of the ATT_DATA word are high
(ATT_DATA = 127), attenuation is infinite and the output
of PCM1712 will be zero.
DSD = H
DSD = L
NAME
MC
MD
ML
Level = 20log
PIN
27
28
26
FUNCTION
Clock for Strobing in Data
Latches Data into the Registers
8-bit Data Word Defining Operation
10
(1 - ATT_DATA/127) dB
Double Speed Dubbing Mode
Normal Mode