CS8416-IS Cirrus Logic, CS8416-IS Datasheet - Page 17

• Manufacturer Part Number: CS8416-IS
• Description: 192 kHZ DIGITAL AUDIO INTERFACE RECEIVER
• Manufacturer: Cirrus Logic

There are some applications where low jitter in the
recovered clock, presented on the RMCK pin, is
important. For this reason, the PLL has been de-
signed to have good jitter attenuation characteris-
tics. In addition, the PLL has been designed to only
use the preambles of the AES3 or S/PDIF stream to
provide lock update information to the PLL. This
results in the PLL being immune to data dependent
jitter affects because the AES3 or S/PDIF pream-
bles do not vary with the data.
In applications where jitter must be minimized,
special attention should be given to reducing the
noise on the analog power supply and ground for
the PLL filter components. Connecting the filter
components directly to AGND will help decrease
jitter.
The PLL has the ability to lock onto a wide range
of input sample rates with no external component
changes.
5.2.1
A special clock switching mode is available that al-
lows the OMCK clock input to replace RMCK
when the PLL becomes unlocked.
In Software mode this feature is enabled by setting
SWCLK bit in Control1 register to a “1”.
In Hardware Mode this feature is always active.
Clock switching is accomplished without spurious
transitions or glitches on RMCK.
OSCLK and OLRCK are derived from the OMCK
input when the clock has been switched and the se-
rial port is in master mode.
When the PLL loses lock, the frequency of the
VCO drops to ~500 kHz. When this system clock
mode is not enabled, the OSCLK and OLRCK will
be based on the VCO when the PLL is not locked
5.2.2
The PLL behavior is affected by the external filter
component values.
DS578PP2
OMCK System Clock Mode
PLL External Components
Figure 5
and
Figure 6
show the
recommended configuration of the two capacitors
and one resistor required. There are two sets of
component values recommended, depending on the
sample rate of the application. (See
default set, called “fast”, accommodates input sam-
ple rates of 96 KHz to 192 Hz with no component
changes. It has the highest corner frequency jitter
attenuation curve, and takes the shortest time to
lock. The alternate component set, called “medi-
um” allows the lowest input sample rate to be 32
kHz, and increases the lock time of the PLL. Lock
times are worst case for an Fs transition from un-
locked state to locking to 192 kHz.
It is important to treat the PLL FLT pin as a low
level analog input. It is suggested that the ground
end of the PLL filter be returned directly to the
AGND pin independently of the digital ground
plane.
5.3
Software Mode
While decoding the incoming AES3 data stream,
the CS8416 can identify several kinds of error, in-
dicated in the Receiver Error register (0Ch).
The errors indicated are:
1) QCRC – CRC error in Q subcode data
2) CCRC – CRC error in channel status data
3) UNLOCK – PLL is not locked to incoming data
4) V – Data Validity bit is set
5) CONF – Input data stream is near error condi-
6) BIP – Biphase encoding error
7) PAR – Parity error in incoming data
32 - 192
96 - 192
Range
(kHz)
stream
tion due to jitter degradation
Table 2. External PLL Component Values
Error Reporting and Hold Function
1 KΩ
3 KΩ
Rflt
220 nF
22 nF
Cflt
10 nF
Crip
1 nF
Settling
11ms
Time
4ms
Table
CS8416
medium
2.) The
fast
17