Driver circuitry

A switching driver apparatus for driving a transducer comprising:

• a plurality of supply nodes for receiving supply voltages defining at least one input voltage;
• a first switching driver having a driver output node, and
• a controller for controlling operation of the first switching driver based on an input signal to generate a drive signal for the transducer at the driver output node;
• wherein the first switching driver comprises:
• capacitor nodes for connecting, in use, to at least first and second capacitors such that the first capacitor is connected between first and second capacitor nodes and the second capacitor is connected between the second capacitor node and a third capacitor node;
• and
• a network of switches for selectively connecting any of the driver output node, the second capacitor node and the third capacitor node to either of a respective pair of said supply nodes, with the first capacitor node connected to the first driver output node, and wherein the network of switches comprises:
• a first switch for selectively connecting the driver output node to a first supply node;
• a second switch for selectively connecting the driver output node to a second supply node;
• a third switch for selectively connecting the second capacitor node to the first supply node;
• a fourth switch for selectively connecting the second capacitor node to the second supply node;
• a fifth switch for selectively connecting the third capacitor node to the first supply node;
• a sixth switch for selectively connecting the third capacitor node to the second supply node;
• and
• a seventh switch for selectively connecting the first capacitor node to the driver output node.

A switching driver apparatus for driving a transducer comprising:

• a plurality of supply nodes for receiving supply voltages defining at least one input voltage;
• a first switching driver having a driver output node, and
• a controller for controlling operation of the first switching driver based on an input signal to generate a drive signal for the transducer at the driver output node;
• wherein the first switching driver comprises:
• capacitor nodes for connecting, in use, to at least first and second capacitors such that the first capacitor is connected between first and second capacitor nodes and the second capacitor is connected between the second capacitor node and a third capacitor node;
• and
• a network of switches for selectively connecting any of the driver output node, the second capacitor node and the third capacitor node to either of a respective pair of said supply nodes, with the first capacitor node connected to the first driver output node;
• wherein each of the switches of the network of switches comprises a NMOS transistor;
• and
• wherein at least some of the NMOS switches comprise a bootstrap circuit.

A switching driver apparatus for driving a transducer comprising:

• a plurality of supply nodes for receiving supply voltages defining at least one input voltage;
• a first switching driver having a driver output node, and
• a controller for controlling operation of the first switching driver based on an input signal to generate a drive signal for the transducer at the driver output node;
• wherein the first switching driver comprises:
• capacitor nodes for connecting, in use, to at least first and second capacitors such that the first capacitor is connected between first and second capacitor nodes and the second capacitor is connected between the second capacitor node and a third capacitor node;
• and
• a network of switches for selectively connecting any of the driver output node, the second capacitor node and the third capacitor node to either of a respective pair of said supply nodes, with the first capacitor node connected to the first driver output node;
• wherein each of the switches of the network of switches comprises a NMOS transistor;
• and
• wherein the network of switches is operable such that, in use, the voltage at least one of the second and third capacitor nodes may go negative and where a switch of the switch network which is connected between one of the second and third capacitor nodes and the second supply node is configured to prevent conduction via a body diode.

A switching driver apparatus for driving a transducer comprising:

• first and second supply nodes for receiving first and second supply voltages defining an input voltage;
• a first driver output node for outputting a drive signal for the transducer,
• capacitor nodes for connecting, in use, to a plurality of capacitors;
• a network of switches selectively connecting said first and second supply nodes to said first driver node or the capacitor nodes, the network of switches being operable such that each of the plurality of capacitors can be selectively connected between the first and second supply nodes to be charged to the input voltage and operable such that the first supply node can be connected to the first driver output node with selectively none, one or more of the plurality of capacitors in a path between the first supply node and the first driver output node;
• a second driver output node for driving a transducer in a bridge-tied-load configuration between the first and second driver output nodes, and
• capacitor nodes for connecting, in use, to a second plurality of capacitors;
• wherein the network of switches is operable such that each of the second plurality of capacitors can be selectively connected between the first and second supply nodes to be charged to the input voltage and operable such that the first supply node can be connected to the second driver output node with selectively none, one or more of the second plurality of capacitors in a path between the first supply node and the second driver output node.

A switching driver apparatus for driving a transducer comprising:

• first and second supply nodes for receiving first and second supply voltages defining an input voltage;
• a first switching driver having a driver output node for outputting a drive signal for the transducer,
• capacitor nodes for connecting, in use, to first and second capacitors;
• and
• a network of switches selectively connecting said first and second supply nodes to said first driver node or the capacitor nodes, the network of switches being operable in a plurality of switch states;
• wherein:
• in one of the plurality of switch states the first capacitor is connected between the first and second supply nodes;
• in one of the plurality of switch states the second capacitor is connected between the first and second supply nodes;
• in one of the plurality of switch states the both the first and second capacitors are connected in series between the first supply node and the driver output node;
• in one of the plurality of switch states just one first and second capacitors is connected in series between the first supply node and the driver output node;
• and
• in one of the plurality of switch states the first supply node is connected to the driver output node with neither of the first and second capacitors in series.

A switching driver comprising:

• first and second switching legs, each switching leg comprising a switching node and a first switch for connecting the switching node of that switching leg to a high side voltage supply and a second switch for connecting the switching node of that switching leg to a low side voltage supply;
• wherein the switching node of the second switching leg is connected to the switching node of the first switching leg via a capacitor and a connection switch;
• and
• wherein the first and second switches of the first switching leg are implemented by first and second NMOS transistors respectively.