WM8740 Wolfson Microelectronics plc, WM8740 Datasheet - Page 14

• Manufacturer Part Number: WM8740
• Description: 24-bit, High Performance 192khz Stereo Dac
• Manufacturer: Wolfson Microelectronics plc

WM8740
8 X FS INPUT SAMPLE RATE
MODES OF OPERATION
HARDWARE CONTROL MODES
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Due to the higher speed of the interface in 8 x fs mode, audio data is input on two pins. The MODE
pin (pin 24) is used as the second input for the right channel data and left data is input on DIN (pin2).
In this mode, software control of the device is not available. The data can be input in two formats, left
or right justified, selectable by ML/I2S and two word lengths (20 or 24 bit), selectable by CSBIWO. In
both modes the data is always clocked in MSB first.
For left justified data the word start is marked by the falling edge of LRCIN. The data is clocked in on
the next 20/24 BCKIN rising edges. This format is compatible with devices such as the PMD100.
For right justified the data is justified to the rising edge of LRCIN and the data is clocked in on the
preceding 20/24 BCKIN rising edges before the LRCIN rising edge. This format is compatible with
devices such as the DF1704 or SM5842.
In both modes the polarity of LRCIN can be switched using MD/DM0.
Differential hardware mode can be used in conjunction with 8fs mode by setting the DIFFHW
unused and must be tied low.
Figure 9 Audio Data Input Format (8 x fs Operation)
Control of the various modes of operation is either by software control over the serial interface, or
by hard-wired pin control. Selection of software or hardware mode is via MODE pin. The following
functions may be controlled either via the serial control interface or by hard wiring of the
appropriate pins.
When the MODE pin is held ‘low’ the following hardware modes of operation are available. In
Hardware differential mode or 8X mode some of these modes/control words are altered or
unavailable.
pin high. In differential 8fs mode the data is input on DIN and output differentially. MODE is
BCKIN (PIN 3)
BCKIN (PIN 3)
LRCIN (PIN 1)
RIGHT AUDIO
LRCIN (PIN 1)
RIGHT AUDIO
LEFT AUDIO
DATA MODE
LEFT AUDIO
DATA MODE
DATA DIN
DATA DIN
(PIN 24)
(PIN 24)
(PIN 2)
(PIN 2)
B23
B23
B22
B22
B23
B23
B21
B21
B22
B22
B20
B20
B21
B21
B19
B19
1/8fs
1/8fs
B20
B20
B19
B19
B2
B2
B1
B1
B2
B2
B0
B0
B1
B1
B0
B0
PD, Rev 4.3, August 2009
B23
B23
B22
B22
B21
B21
Production Data
B20
B20
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