Switching drivers with capacitive voltage generation operable in different capacitor biasing regimes

A switching driver for driving a load with an output drive signal based on an input signal comprising:

• a supply input node configured to receive an input supply voltage that can vary in use;
• and
• an output stage configured to switch at least one driver output node between selected switching voltages with a controlled duty-cycle so as to generate the output drive signal at the at least one driver output node, wherein the output stage is operable in a plurality of different driver modes in which the switching voltages are different in the different driver modes;
• wherein the switching driver comprises a capacitor configured as part of a capacitive voltage generator for generating a voltage that can be used as a switching voltage, wherein, in use, the capacitor is biased to a capacitor voltage and the capacitor has a voltage rating for a safe operating voltage;
• and
• wherein the switching driver is configured such that biasing of the capacitor is dynamically varied in use based on the magnitude of the input supply voltage to vary the relationship between the capacitor voltage and the input supply voltage to maintain the magnitude of the capacitor voltage below the voltage rating.

A switching driver for driving a load with an output drive signal based on an input signal comprising:

• an output stage configured to switch at least one driver output node between selected switching voltages with a controlled duty-cycle so as to generate the output drive signal at the at least one driver output node,
• wherein the switching driver comprises a capacitor configured as part of a capacitive voltage generator for generating a voltage that can be used as a switching voltage;
• wherein the switching driver is configured to be operable:
• in a first regime in which the capacitor is biased to a capacitor voltage such that a ratio of the capacitor voltage to an input supply voltage has a first value;
• and
• in a second regime in which a ratio of the capacitor voltage to the input supply voltage has a value lower than the first value;
• wherein the capacitor has a capacitor voltage limit for a safe operating voltage such that, if the switching driver were operated in the first regime for a maximum expected value of input voltage, the capacitor voltage would exceed the capacitor voltage limit;
• and
• wherein the switching driver is configured to selectively operate in the first regime or the second regime based on whether the capacitor voltage when operating in the first regime would exceed the capacitor voltage limit, so as to maintain the capacitor voltage within the voltage rating of the safe operating voltage.