DDX-4100 Errata
DDX Multichannel
Digital Audio Processor
ERRATA
A] When using the sample rate converter (SRC), it is mandatory to apply a
valid input signal to the DDX-4100 prior to unmuting. Failure to do so will
result in large DC offsets applied to speaker outputs which may damage
loudspeakers.
To ensure proper operation using the S/PDIF input, be sure to poll the “S/PDIF
Status” bit (register 0x77, bit 1 which determines S/PDIF lock) indicating a valid
input signal prior to unmuting. Bit 1 will report logic ‘0’ for a valid S/PDIF input
signal or logic ‘1’ for an invalid signal. Delay unmuting until after a valid signal is
detected.
To ensure proper operation using the serial I2S inputs or AC97, valid clock
signals must be applied to DDX-4100 pins 3,4 (LRCKI/SYNC, BICKI/BIT_CLK)
prior to unmuting. The “SRC Status” bit (register 0x77, bit 0 which determines
SRC lock), does not provide a correct indication prior to receiving a valid input
signal. The “SRC Status” bit 0 will indicate SRC lock , logic ‘0’, whether or not
valid input signals are applied. Subsequent to receiving a valid input signal, the
“SRC Status” bit operates as intended, i.e. removing the input signal will cause
an out-of-lock indication.
B] It is recommended to configure the device using a 24.576MHz crystal.
Be sure the “PLL_Factor” bit in CRA is cleared (Configuration Register A,
Subaddress 0x5B, bit 7= ‘0’). This is the default value following hardware
RESET (pin 7) being deasserted or writing to the “Reset Register” (Subaddress
0x00) via I2C. The alternate 6.144MHz crystal is not recommended. When
using the 6.144MHz crystal, difficulties have been observed following power-up
which may appear as I2C related. These include unexpected muting or failure to
un-mute when commanded, poor S/N ratio which improves after power cycling,
or high DC output with no audio. These operational difficulties can be solved by
substituting a 24.576MHz crystal and clearing the PLL_Factor.
C] VDD should be limited to 3.4V maximum for proper operation.
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Copyright Apogee Technology, Inc 2001
(All Rights Reserved)
January 2002
DOC #07010002-03