Adaptive Mobile-Device Amp Embeds Advanced Algorithms for Immersive Audio

With the increasing use of mobile devices such as smartphones and tablets for music, podcasts, movies, and gaming, the sound quality and power efficiency of these units are taking on greater significance. To provide a more “immersive” audio experience for the user, the Cirrus Logic CS35L45 smart power amp delivers higher excursion for high-peak loudness, improved dynamic range for more punch and bass precision, less noise and audible artifacts, and more tonal balance at all volume levels (Fig. 1).

1. The Cirrus Logic CS35L45 smart power amplifier for mobile devices incudes a DSP engine that implements adaptive, enhanced algorithms for “bigger” sound in the context of battery status.

This 15-V boosted Class D audio amplifier features I²S and TDM audio interfaces along with an SPI/I²C control data interface. It also contains an integral digital signal processor (DSP). The device can be easily integrated into a stereo or multi-speaker playback solution to improve performance in mid-tier devices without requiring an upgrade to the device’s speakers, yet enables delivery of richer audio, according to Cirrus Logic.

To achieve these goals, the CS35L45 incorporates an adaptive battery-management scheme to drive higher output power across all battery conditions, resulting in up to 30% higher peak loudness compared to its own previous generation boosted amplifier (Fig. 2). The IC features 7-W output-power capability and 15-V overboost for higher peak power across the frequency spectrum, thus proving more tonal balance at all volume levels, better dynamics, and more spatial range and timbre.

2. The adaptive power boost incorporates elements that indicate its “big-picture” situational awareness, enabling higher peak power at all frequencies while “looking ahead” for sudden audio signal spikes to protect the battery.

Since the CS35L45 amplifier can draw high levels of battery current, it includes built-in battery current and voltage monitoring to deliver high output power—but only when required to reproduce the source audio content (Fig. 3). Further, its proprietary adaptive battery-management technology helps it to “look ahead” to sudden audio signal spikes to protect the battery, prevent audio pumping and clipping, and maximize the audio performance at all volume levels, and do so without audible artifacts.

3. The power amplifier uses next-generation algorithm tuning with Predictive Input Current Limiting (PICL) to push speakers to their maximum limits while keeping them within safe limits.

The IC also offers protection, as its speaker-protection algorithm allows those speakers to be pushed to their maximum while keeping them within safe limits. On-chip firmware adds equalization and psychoacoustic enhancements to maximize performance from small speakers.

The CS35L45 is offered in a commercial-grade, 0.4-mm pitch, 36-ball wafer-level chip-scale package (WLCSP) and rated for operation from −40 to +85°C. More information on the audio amplifier is available at https://www.cirrus.com/products/cs35l45.