Wolfson has overcome the challenge of combining analog-power-management functions into a mixed-signal audio block that has fast digital signal with steep edge rates. Audio-digital sections are sensitive to jitter, and power-management functions are sensitive to noise, but Wolfson has met the significant design challenges of combining these functions on one chip. Additional functions include an on-chip FLL (frequency-locked loop), a real-time clock, six dc/dc converters, four low-dropout regulators, a battery charger, two white-LED drivers, and an auxiliary ADC in a 7×7-mm package. The regulators operate at more than 90% efficiency; the buck converters operate at 2 MHz, and the boost converters operate at 1 MHz.
The audio part of the subsystem extends the audio quality. Careful clocking and pop-and -click suppression improve the audio quality and reduce the external component count. The WM8350 features an A-weighted SNR (signal-to-noise ratio) of 98 dB at 48 kHz and a THD (total harmonic distortion) of —84 dB for the DAC; the respective figures for the ADC are 95 and —80 dB. The DAC’s playback power consumption of 18 mW extends battery life.
