CIRCUITS AND METHODS FOR CONTROLLING TRANSIENTS DURING AUDIO DEVICE POWER-UP AND POWER-DOWN, AND SYSTEMS USING THE SAME

摘要

Circuitry for ramping a voltage across a load (506) includes a charging circuit (500) for charging a capacitor (501) to generate a ramp-up wave form. Circuitry (511) selectively decouples a first driver (510) from load (506) during a ramping up mode and couples first driver (510) to load (506) during a normal operating mode. Ramp up driver (507a) is selectively coupled to the load (506) during the ramp-up mode for ramping up the voltage across load (506) in response to the ramp-up wave form generated by charging circuitry (500). A discharge circuit (503d, 514a,b) discharges capacitor (501) to generate a power-down wave form. Circuitry (511) selectively decouples a first driver (501) from output load (506) during the ramping down of the voltage across output load (506). A ramp-down driver (507b) selectively ramps-down the voltage across output load (506) in response to the ramp-down wave form generated by discharge circuitry (503d, 514a,b).