Cirrus Logic CS4399, Manual

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DS1113F1 29
CS4399
4.5 Clocking Architecture
3. Write to HPDETECT_RISE_DBC_TIME and HPDETECT_FALL_DBC_TIME (see p. 89 ) to enable debounce for
presence detect plug/unplug.
4. Set HPDETECT_CTRL to 11 to enable the HPDETECT functions.
The interrupt status bits can be found in Section 7.6.1 . The status does not contain an event-capture latch (a read always
yields the current condition).
4.5 Clocking Architecture
4.5.1 Master Clock (MCLK) Sources
The MCLK is required by the CS4399 to operate any functionality associated with control, serial-port operation, or data
conversion. Depending on the setting of
MCLK_SRC_SEL (see p. 74 ), the MCLK can be provided by one of following
methods:
• Sourced from a crystal oscillator between XTI/MCLK and XTO pins (see Fig. 4-9 ), then used directly as MCLK_INT
• Externally sourced through the XTI/MCLK input pin (see Fig. 4-10 )
• PLL reference clock is provided through the XTI/MCLK input pin (see Fig. 4-10 ), then use internal PLL to convert
into MCLK_INT
• Use internal RCO as MCLK. This mode can support HP detection and I 2 C communication. DAC playback is not
supported.
Figure 4-9. System Clocking—Crystal Mode
Figure 4-10. System Clocking—External MCLK Mode
If XTAL is used, the supported crystal characteristics and frequencies are listed in Table 3-11 . Based on the crystal
selection, XTAL_IBIAS must be set properly before powering up. The XTAL_IBIAS information can be found in
Section 5.3 . PDN_XTAL is cleared to start the crystal oscillator. PDN_XTAL is set to power down the crystal oscillator. The
XTAL_READY_INT and XTAL_ERROR_INT status bits indicate the status of crystal operation after power-up. At
t
XTAL_pup
after the crystal oscillator is powered up, if the crystal is started successfully and ready to be used, XTAL_READY_INT is
set; if the crystal is started unsuccessfully, XTAL_ERROR_INT is set. The two bits are mutually exclusive when set. Both
status bits have corresponding interrupt status bits and interrupt mask bits. To be informed on the crystal status at
t
XTAL_
pup
after power-up, unmask both interrupts before powering up the crystal.
XTAL
XTI/MCLK
XTO
External MCLK
System
Clock
XTI/MCLK
XTO