CS43130 Datasheet, PDF (24/137 Pages) Cirrus Logic – 130-dB, 32-Bit High-Performance DAC with Integrated Headphone Driver

CS43130
4 Functional Description
4 Functional Description
This section describes the general theory of operation of the CS43130, 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 Amplifier Output”
• Section 4.4, “Alternate Headphone Inputs”
• Section 4.5, “Headphone Presence Detect and Output Load Detection”
• Section 4.6, “Clocking Architecture”
• Section 4.7, “Clock Output and Fractional-N PLL”
• Section 4.8, “Filtering Options”
• Section 4.9, “Audio Serial Port (ASP)”
• Section 4.10, “DSD Interface”
• Section 4.11, “DSD and PCM Mixing”
• Section 4.12, “Standard Interrupts”
• Section 4.13, “Control Port Operation”
4.1 Overview
4.1.1 Analog Outputs
The analog output block includes separate pseudodifferential headphone Class H amplifiers 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 amplifier supply can be ±VCP, or ±VP_LDO (either ±3.0 V with HV_EN = 1
or ±2.6 V with HV_EN = 0).
The inverting architecture eliminates the need for large DC-blocking capacitors and allows the amplifier to deliver more
power to HP loads at lower supply voltages. This adaptive power supply scheme converts traditional Class AB amplifiers
into more power-efficient Class H amplifiers.
4.1.2 Alternate Headphone Inputs
The alternate headphone inputs provide an integrated selectable path to interface between the system codec output and
the headphone connector, which allows for lower-power operation in applications such as voice or compressed music
playback. These inputs eliminate the need for an external audio switch and prevent the high-fidelity headphone outputs of
CS43130 from degradation by the external audio switch.
4.1.3 Headphone Detection
The CS43130 detects the presence of a headphone and notifies the application processor to wake up through an interrupt
event.
4.1.4 Headphone Impedance Measurement
The CS43130 detects headphone impedance information at low frequencies, which can be used to adjust the system
properly to accommodate different load conditions. One example is to adjust signal chain gain to avoid distortion.
The CS43130 also provides impedance measurement functions to evaluate the headphone load within 20 Hz to 20 kHz.
A specific frequency is selected and the impedance measurement process is initiated by setting the register. Through a
series of interrupt events, the CS43130 notifies application processor to retrieve the impedance information after
completion.
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