DC-to-DC converter operating in a discontinuous mode

A voltage boosting circuit, operable from first and second supply voltages, said first supply voltage being a positive supply voltage and said second supply voltage connection providing a chip ground, comprising:

• a first node connectable to said first supply voltage through an external inductor;
• a connection for providing a gate drive signal to a switching transistor which can selectively connect said first node to said second power supply voltage;
• connections for providing an output diode which is interposed between said first node and an output node;
• a first comparator connected to monitor the voltage of said output node,
• a second comparator connected to monitor the voltage of said first node;
• a third comparator connected to monitor the current through the output diode;
• logic connected to intermittently turn on said switching transistor for a duration determined by said second comparator and only when said third comparator indicates that current through said inductor and said output diode has ceased while said first comparator indicates that additional current through said output diode is needed;
• whereby said output node provides a third power supply voltage which is not equal to said first nor to said second supply voltage.

A voltage boosting circuit, operable from first and second supply voltage connections, said first supply voltage being a positive supply voltage and said second supply voltage connection providing a chip ground, comprising:

• a first node connectable to said first supply voltage through an external inductor;
• a switching transistor connected to connect said first node to said second power supply voltage;
• an output diode, interposed between said first node and an output node;
• a first comparator connected to monitor the voltage of said output node,
• a second comparator connected to monitor the voltage of said first node;
• a third comparator connected to monitor the current through the output diode;
• logic connected to intermittently turn on said switching transistor to store energy in the magnetic field of said inductor, but only when said third comparator indicates that current through said inductor and said output diode has ceased;
• whereby said output node provides a third power supply voltage which is greater than said first supply voltage.

A voltage boosting circuit, operable from first and second supply voltage connections, said first supply voltage being a positive supply voltage and said second supply voltage connection providing a chip ground, comprising:

• a first node connectable to said first supply voltage through an external inductor;
• a switching transistor connected to connect said first node to said second power supply voltage;
• an output diode, interposed between said first node and an output node;
• a first comparator connected to monitor the voltage of said output node,
• a second comparator operatively connected to monitor the current through said switching transistor;
• a third comparator connected to monitor the current through the output diode;
• logic connected to intermittently turn on said switching transistor to increase the voltage drop across said inductor, but only when said third comparator indicates that current through said inductor and said output diode has ceased;
• whereby said output node provides a third power supply voltage which is greater than said first supply voltage.

A buck conversion circuit, operable from first and second supply voltages, comprising:

• a series combination of a switching transistor and an output diode, defining a first node at a connection thereof, and connected between said first and second supply voltages;
• an external inductor operatively connected between said first node and an output node;
• a first comparator operatively connected to monitor the voltage of said output node,
• a second comparator operatively connected to monitor the current through said switching transistor;
• a third comparator operatively connected to monitor the current through the output diode;
• and
• logic connected to intermittently turn on said switching transistor to increase the back voltage of said inductor, but only when said third comparator indicates that current through said output diode has ceased;
• whereby said output node provides a third power supply voltage which is intermediate between said first and second supply voltages, while avoiding excess power consumption.

A DC-to-DC converter, connected to receive power from two supply connections and to provide a power supply on an output node at a voltage different from both the power supply connections, comprising

• an inductor driven by a switch to cyclically charge,
• a discharge diode of the energy stored in the inductor on an output node,
• a capacitor connected between the output node and one or the other of the supply rails, and
• a control circuit for regulating the output voltage, which comprises
• a first comparator of the output voltage enabling and disabling the closing of said switch depending on whether the output voltage is lower or higher than a reference voltage and
• means, for controlling the switching of said switch, which comprises
• a second comparator of the voltage across said switch, generating a turn-off signal when said voltage rises above a preset value;
• a third comparator of the discharge current of the inductor through said diode, generating a confirmation signal of an OFF state of said switch until the current through said diode has become null;
• and
• means for masking said turn-off signal until turn-on of said switch is enabled by said first comparator.

A method for operating a voltage conversion circuit to generate on an output node a third power supply voltage from first and second power supply voltages, using an inductor, a switching transistor configured to drive current through said inductor from first and second supply voltages, and an output diode connected between one terminal of said inductor and one of said supply voltages, comprising the steps of:

• monitoring the voltage of said output node, substantially continually, using a first comparator;
• monitoring the voltage of a node intermediate between said inductor and said diode, substantially continually, using a second comparator;
• monitoring the current through the output diode, substantially continually, using a third comparator;
• intermittently turning on said switching transistor, to increase the voltage drop across said inductor, for a duration determined by said second comparator, only when said third comparator indicates that current through said inductor and said output diode has ceased while said first comparator indicates that additional current through said output diode is needed.