Portable Audio DAC with Integrated Class D Speaker Driver

The CS43L22 is the newest addition to the Cirrus Logic low power product line: a highly integrated, low power stereo DAC with a headphone and Class D speaker amplifier. Building on the success of the current low power converter line, Cirrus Logic has incorporated features such as PWM speaker drivers, an on-board charge pump, and flexible voltage supply configurations into the CS43L22.

Integrated solutions such as the CS43L22 helps simplify the designer’s job of creating a high quality signal path for portable audio devices, while eliminating the need for external components such as regulators for multiple power supplies, buck converters for direct battery connection, and amplifiers for the stereo speaker. Supplementary features such as analog bypass, and digital signal processing engine as well as a beep generator on the DAC output path allows the system architect to focus on other areas that may need improvement in their design.

Setting the precedent for portable converter integration on the previous generation CODECs and DACs with ground centered outputs and an on-board charge pump, the CS43L22 is capitalizing on those innovations with the additions of items such as MCLK support for 12, 24, and 27MHz, as well as allowing direct battery connection for the PWM amplifier, with single power supply operation on the remainder of the chip.

This combination of PWM stereo speaker driver, ground centered outputs, and broad MCLK support without a power consuming PLL is unique to the market.

The DAC output path includes a digital signal processing engine with various fixed function controls. Tone Control provides bass and treble adjustment of four selectable corner frequencies. The Digital Mixer provides independent volume control for both the ADC output and PCM input signal paths, as well as a master volume control. Digital Volume controls may be configured to change on soft ramp transitions while the analog controls can be configured to occur on every zero crossing. The DAC also includes de-emphasis, limiting functions and a BEEP generator delivering tones selectable across a range of two full octaves. The flexibility, integration and performance of the CS43L22 are all packaged in a 40-Pin QFN that delivers 13 mW quiescent power consumption at 1.8 Volts.

To further help with design integration, the CS43L22 is register and Pin to Pin compatible to the CS42L52. This allows to have a platform of designs that can be replicated for different applications  and across multiple end-products.