CS4399 datasheet(29/111 Pages) CIRRUS

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DS1113F1

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 I2C 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 tXTAL_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 tXTAL_

pup after power-up, unmask both interrupts before powering up the crystal.

XTAL

XTI/MCLK

XTO

External MCLK

System

Clock

XTI/MCLK

XTO

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