DIR9001-Q1 Datasheet, PDF (16/30 Pages) Burr-Brown (TI) – 96-kHz, 24-Bit Digital Audio Interface Receiver

DIR9001-Q1
SLLS843A – JUNE 2007 – REVISED FEBRUARY 2008
www.ti.com
XTI Clock Source and Oscillation Amplifier Description
This clock, driven by the built-in oscillation amplifier or input into the XTI pin from an external clock, is defined as
the XTI source. A 24.576-MHz fundamental resonator or external 24.576-MHz clock is used as the XTI source.
The DIR9001-Q1 requires an XTI source for following purposes:
• The measurement reference clock of actual-sampling-frequency calculator
• The clock source for the XTI source mode (CKSEL = H setting)
(That is, the DIR9001-Q1 does not require an XTI source if it is only decoding the biphase input signal.)
The XTI clock source is supplied in one of the following two ways; the details are described in Figure 9.
• Setting up an oscillation circuit by connecting a resonator with the built-in amplifier
• Applying a clock from an external oscillator circuit or oscillator module
To set up an oscillation circuit by connecting a resonator with the built-in amplifier:
• Connect a 24.576-MHz resonator between the XTI pin and XTO pin.
• The resonator should be a fundamental-mode type.
• A crystal resonator or ceramic resonator can be used.
• The load capacitor C_L1, C_L2, and the current-limiting resistor R_d depend on the characteristics of the
resonator.
• No external feedback resistor between the XTI pin and XTO pin is required, as an appropriate resistor is
incorporated in the device.
• No load other than the resonator is allowed on the XTO pin.
To connect an external oscillator circuit or oscillator module:
• Provide a 24.576-MHz clock on the XTI pin
• Note that the XTI pin is not 5-V tolerant; it is simple CMOS input.
• The XTO pin must be open.
Resonator
C_L1
R_d
C_L2
Crystal
OSC
Circuit
24.576-MHz
Internal Clock
XTI
External
Clock
Crystal
OSC 24.576-MHz
Circuit Internal Clock
XTI
XTO
DIR9001-Q1
Resonator Connection
Must Be
Open
XTO
DIR9001-Q1
External Clock Input Connection
Figure 9. XTI and XTO Connection Diagram
B0241-01
Description of oscillation amplifier operation:
• The built-in oscillation amplifier is always working.
• If the XTI source clock is not used, then the XTI pin must be connected to DGND.
• For reducing power dissipation, it is recommended to not use the XTI source clock.
In XTI mode (CKSEL = H), output clocks (SCKO, BCKO, LRCKO) are generated from XTI source clock.
The relation between output clock frequency (SCKO, BCKO, LRCKO) and the XSCK pin setting in XTI source
mode is shown in Table 6.
Table 6. SCKO, BCKO, LRCKO Output Frequency at XTI Mode
XTI FREQUENCY
24.576 MHz
OUTPUT CLOCK FREQUENCY IN XTI SOURCE MODE (CKSEL = H)
SCKO
BCKO
LRCKO
24.576 MHz
6.144 MHz
96 kHz
16
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