Abstract: Power-up and power-down transient suppression are provided for an audio digital-to-analog converter with a single ended output to prevent annoying pops which accompany switching an audio system on and off. Power-up suppression is achieved by clamping an output signal to ground, driving the audio channel to ground, releasing the clamp and driving the audio channel gradually to its quiescent (zero signal) value. Power-down suppression is provided by using a positive feedback amplifier to accelerate current drain initiated by a constant current source used to bleed off the charge on output capacitor. The audio digital-to-analog converter sets operational mode based on ratios of a master clock to a channel selection clock. The techniques disclosed apply readily to the outputs received from CDs, CD-ROMs, DAT and other digital recording media.

Abstract: Power-up and power-down transient suppression are provided for an audio digital-to-analog converter with a single ended output to prevent annoying pops which accompany switching an audio system on and off. Power-up suppression is achieved by clamping an output signal to ground, driving the audio channel to ground, releasing the clamp and driving the audio channel gradually to its quiescent (zero signal) value. Power-down suppression is provided by using a positive feedback amplifier to accelerate current drain initiated by a constant current source used to bleed off the charge on output capacitor. The audio digital-to-analog converter sets operational mode based on ratios of a master clock to a channel selection clock.