Cirrus Logic AN335 - Manual (Page 6)

6 AN335REV1
AN335
which is required to operate in slave mode.
– The CM-2 provides a LRCK signal at 48 kHz (Sampling Rate or Fs) to an external audio source/sink,
which is required to operate in slave mode.
– The external audio source/sink provides digital audio data to / receives from the CM-2 module.
– An external active-low reset signal in accordance with the hardware specifications is applied.
• There are two deviations from the standard reference design that can be safely made at the designer's
option:
– Refer to U4 on page 2 of 7 of the reference design. This device is used to select between an external
audio master clock and the local VCXO generated master audio clock. This MUX can be omitted
when use of an external master clock is not required. The master audio clock can be connected from
the VCXO to the CobraNet processor. The series termination resistor should be retained. If the clock
will be used by more than one load then it should be buffered. Application Note AN312 should be
carefully read and understood if other than the standard clocking mode 0x00 will be used.
– Refer to U11 and U10C on page 4 of 7 of the reference design. The audio word clock (FS1) is taken
from pin 22 or pin 14 of the CobraNet chip depending on whether or not a 16x16 channel device is
used. This circuit will automatically select the correct pin based on clock activity. If the design does
not require this flexibility (most do not), then FS1 can be hardwired from Pin 14 for 16x16 channel
devices or from Pin 22 for other devices. R53, the series termination resistor, should b retained.