Cirrus Logic CS4399, Manual

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DS1113F1 21
CS4399
4 Functional Description
4 Functional Description
This section describes the general theory of operation of the CS4399, tracing the signal and control flow through the
various blocks within the device. It comprises the following sections:
• Section 4.1 , “ Overview ”
• Section 4.2 , “ Analog Outputs ”
• Section 4.3 , “ Class H Output ”
• Section 4.4 , “ Headphone Presence Detect ”
• Section 4.5 , “ Clocking Architecture ”
• Section 4.6 , “ Clock Output and Fractional-N PLL ”
• Section 4.7 , “ Filtering Options ”
• Section 4.8 , “ Audio Serial Port (ASP) ”
• Section 4.9 , “ DSD Interface ”
• Section 4.10 , “ DSD and PCM Mixing ”
• Section 4.11 , “ Standard Interrupts ”
• Section 4.12 , “ Control Port Operation ”
4.1 Overview
4.1.1 Analog Outputs
The analog output block includes separate pseudodifferential output. An on-chip inverting charge pump creates a positive
and negative voltage equal to the input, allowing an adaptable, full-scale output swing centered around ground. The
resulting internal supply can be ±VCP, or ±VP_LDO (either ±3.0 V with HV_EN = 1 or ±2.6 V with HV_EN = 0).
4.1.2 Headphone Detection
The CS4399 detects the presence of a headphone and notifies the application processor to wake up through an interrupt
event.
4.1.3 Audio Interfaces and Supported Formats
There are two serial input ports on the CS4399, the audio serial port (ASP) and the auxiliary serial port (XSP). The ASP
on the CS4399 supports I
2 S, TDM, and DoP (DSD over PCM) formats up to a 384-kHz sample rate. The XSP on the
CS4399 supports the DoP format up to a 352.8-kHz sample rate.
The CS4399 also has a dedicated DSD interface to support up to 128•Fs. The DSD interface shares pins with the XSP.
4.1.4 System Clocking
The CS4399 internal MCLK can be sourced from three options:
• Direct MCLK/crystal mode. The internal MCLK is provided through XTI/MCLK pin directly or generated by crystal
oscillator.
• PLL mode. A PLL reference CLK is provided externally through XTI/MCLK. The PLL is configured, and output is
used as the internal MCLK.
• RCO mode. An internal RCO is used as the internal MCLK. This mode can support HP detection and I
2
C
communication. DAC playback function is not supported.
The clock output is provided for audio applications that require high quality audio rate system clock. This clock output can
be sourced from the following two options:
• The clock generated by the CS4399 crystal oscillator.
• Output of the internal Fractional-N PLL that refers to MCLK input. See
Section 4.6.1 for supported frequencies.