This application relates to methods and apparatus for driving a transducer connected between two output nodes in a bridge-tied-load configuration. A driver receives first and second supply voltages and has charge pumps that generate respective first and second boosted voltages. The driver is operable in a first driver mode in which each output node is modulated between the first and second supply voltage; a second driver mode in which one output nodes is modulated between the first and second supply voltages and the other output node is modulated between either the first boosted voltage and the first supply voltage or between the second supply voltage and the second boosted voltage; and a third driver mode in which one of the output nodes is modulated between the first supply voltage and the first boosted voltage and the other output node is modulated between the second supply voltage and the second boosted voltage.

This application relates to methods and apparatus for multichannel drivers for driving transducers in different channels. A multichannel driver has a plurality of output stages configured such that two output nodes can be modulated between selected switching voltages with a controlled duty cycle to generate a differential output signal across a respective transducer, each output stage being operable with different switching voltages in different modes of operation. A first set of two or more of the output stages are arranged to receive a voltage output by a capacitive voltage generator to use as a switching voltage. A controller is configured to control the mode of operation and duty-cycle of each of the output stages based on a respective input signal and also based on operation of the other output stages of the first set.

This application relates to methods and apparatus for clipping prevention. A driver apparatus for driving a transducer has a switching driver configured to switch at least one output node between different switching voltages with a controlled duty-cycle to drive an output signal across the transducer. A clipping prevention controller is configured to control a gain applied to the input signal so as to provide limiting of the input signal to avoid clipping of the output signal. The clipping prevention controller is configured to dynamically control at least one limiting threshold used to determine when to apply limiting of the input signal based on an indication of load resistance of the transducer and the input voltage to the switching driver.