CS47L85 datasheet(45/370 Pages) CIRRUS

45 / 370 page

CS47L85

Rev 4.3

DIGITAL AUDIO CORE

The CS47L85 uses a core architecture based on all-digital signal routing, making digital audio effects available on all signal

paths, regardless of whether the source data input is analogue or digital. The digital mixing desk allows different audio

effects to be applied simultaneously on many independent paths, whilst also supporting a variety of sample rates

concurrently. This helps support many new audio use-cases. Soft mute and un-mute control allows smooth transitions

between use-cases without interrupting existing audio streams elsewhere.

The CS47L85 digital core provides an extensive capability for programmable signal processing algorithms. The DSP can

support functions such as wind noise, side-tone and other programmable filters. A wide range of application-specific filters

and audio enhancements can also be implemented, including Dynamic Range Control (DRC), Multi-band Compression

(MBC), and Virtual Surround Sound (VSS). These digital effects can be used to improve audibility and stereo imaging while

minimising supply current.

The digital core also provides signal processing capability for sensor hub functions of the CS47L85. Sensors and

accessories can be connected through 3 master I2C interfaces; the programmable DSP, together with peripheral timer and

event logging functions, enables applications to use these inputs to support increased contextual awareness, including

advanced motion sensing and navigation functionality.

The Cirrus Logic Ambient Noise Cancellation (ANC) processor within the CS47L85 provides the capability to improve the

intelligibility of a voice call by using destructive interference to reduce the acoustic energy of the ambient sound. The Cirrus

Logic ANC technology supports receive (RX) path noise cancellation; Transmit (TX) path noise reduction, and multi-mic

Acoustic Echo Cancellation (AEC) algorithms are also supported. The CS47L85 is ideal for mobile telephony, providing

enhanced voice communication quality for both near-end and far-end users in a wide variety of applications.

Highly flexible digital mixing, including mixing between audio interfaces, is possible. The CS47L85 performs multi-channel

full-duplex asynchronous sample rate conversion, providing use-case flexibility across a broad range of system architectures.

Automatic sample rate detection is provided, enabling seamless wideband/narrowband voice call handover.

Dynamic Range Controller (DRC) functions are available for optimising audio signal levels. In playback modes, the DRC

can be used to maximise loudness, while limiting the signal level to avoid distortion, clipping or battery droop, in particular

for high-power output drivers such as speaker amplifiers. In record modes, the DRC assists in applications where the signal

level is unpredictable.

The 5-band parametric equaliser (EQ) functions can be used to compensate for the frequency characteristics of the output

transducers. EQ functions can be cascaded to provide additional frequency control. Programmable high-pass and low-pass

filters are also available for general filtering applications such as removal of wind and other low-frequency noise.

DIGITAL INTERFACES

Four serial digital audio interfaces (AIFs) each support PCM, TDM and I2S data formats for compatibility with most industry-

standard chipsets. AIF1 and AIF2 support eight input/output channels; AIF3 and AIF4 support two input/output channels.

Bidirectional operation at sample rates up to 192kHz is supported.

12 digital PDM input channels are available (six stereo interfaces); these are typically used for digital microphones, powered

from the integrated MICBIAS power supply regulators. Four PDM output channels are also available (two stereo interfaces);

these are typically used for external power amplifiers. Embedded mute codes provide a control mechanism for external

PDM-input devices.

The CS47L85 features a MIPI-compliant SLIMbus interface, providing eight channels of audio input/output. Mixed audio

sample rates are supported on the SLIMbus interface. The SLIMbus interface also supports read/write access to the

CS47L85 control registers.

An IEC-60958-3 compatible S/PDIF transmitter is incorporated, enabling stereo S/PDIF output on a GPIO pin. Standard

S/PDIF sample rates of 32kHz up to 192kHz are all supported.

Control register access, and high bandwidth data transfer, is supported by two slave SPI interfaces and a slave I2C control

interface. The SPI interfaces operate up to 26MHz; the I2C slave interface operates up to 3.4MHz. Full access to the register

map is also provided via the SLIMbus port.

The CS47L85 incorporates three master I2C interfaces, offering a flexible capability for additional sensor / accessory input.

Typical sensors include accelerometers, gyroscopes and magnetometers for motion sensing and navigation applications.

Other example accessories include barometers, or ambient light sensors, for environmental awareness.

OTHER FEATURES

The CS47L85

incorporates two 1kHz tone generators which can be used for ‘beep’ functions through any of the audio signal

paths. The phase relationship between the two generators is configurable, providing flexibility in creating differential signals,

or for test scenarios.

A white noise generator is provided, which can be routed within the digital core. The noise generator

can provide ‘comfort

noise’ in cases where silence (digital mute) is not desirable.

CS47L85 Datasheet(PDF) 45 Page - Cirrus Logic

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