PFM-PWM DC-DC converter providing DC offset correction to PWM error amplifier and equalizing regulated voltage conditions when transitioning between PFM and PWM modes

A method of controlling the operation of a multi-mode DC-DC converter for supplying a regulated DC output voltage to a load, said multi-mode DC-DC converter including

• an output power switching stage having upper and lower power switches coupled between an input voltage terminal and a reference voltage terminal and having a common node therebetween coupled by way of an output inductor to an output node from which said regulated DC output voltage is supplied,
• a control circuit for controlling switching of said upper and lower power switches of said output power switching stage for respectively different modes of operation of said multi-mode DC-DC converter in accordance with respectively different switching control signals applied thereto, and
• a plurality of switching control signal generators, which are operative to generate said respectively different switching control signals, in response to which said control circuit controls switching of said upper and lower power switches of said output power switching stage during said respectively different modes of operation of said multi-mode DC-DC converter, said method comprising the steps of:
• (a) monitoring an electrical parameter of one of said plurality of switching control signal generators;
• and
• (b) in the course of a transition between respectively different modes of operation of said converter, controlling the operation of said one of said plurality of switching control signal generators, in accordance with the electrical parameter monitored in step (a) so as to prevent an anomaly in said DC output voltage for said respectively different modes of operation of said converter.

For use with a pulse width modulation (PWM) mode to pulse frequency modulation (PFM) mode DC-DC converter for supplying a regulated DC output voltage to a load, said PWM mode to PFM mode DC-DC converter including

• an output power switching stage having upper and lower power switches coupled between an input voltage terminal and a reference voltage terminal and having a common node therebetween coupled by way of an output inductor to an output node from which said regulated DC output voltage is supplied;
• a control circuit for controlling switching of said upper and lower power switches of said output power switching stage for said PWM and PFM modes of operation of said converter in accordance with respective PWM and PFM switching control signals applied thereto;
• and
• PWM and PFM switching control signal generators, which are operative to respectively generate PWM and PFM switching control signals, in response to which said control circuit controls switching of said upper and lower power switches of said output power switching stage during said PWM and PFM modes of operation of said converter, said PWM switching control signal generator including an error amplifier;
• the improvement comprising:
• a DC offset voltage correction circuit, that is coupled with said error amplifier, and is operative to place a DC offset correction voltage across said error amplifier at the time of said transition from PFM mode operation to PWM mode operation of said converter, that is effective to compensate for one or more DC offset voltages in a voltage regulation path of said PWM waveform generator.

A multi-mode DC-DC converter for supplying a regulated DC output voltage to a load comprising:

• an output power switching stage having at least one power switch coupled between an input voltage terminal and a reference voltage terminal and having a node coupled by way of an output inductor to an output node from which said regulated DC output voltage is supplied;
• a control circuit for controlling switching of said at least one power switch of said output power switching stage for respectively different modes of operation of said multi-mode DC-DC converter in accordance with respectively different switching control signals applied thereto;
• a plurality of switching control signal generators, which are operative to generate said respectively different switching control signals, in response to which said control circuit controls switching of said at least one power switch of said output power switching stage during said respectively different modes of operation of said multi-mode DC-DC converter;
• and
• a mode transition control circuit, coupled with said plurality of switching control signal generators, and being operative to prevent an anomaly in said DC output voltage at a transition between respectively different modes of operation of said multi-mode DC-DC converter.

A method of controlling the operation of a multi-mode DC-DC converter for supplying a regulated DC output voltage to a load, said multi-mode DC-DC converter including:

• an output power switching stage having at least one power switch coupled between an input voltage terminal and a reference voltage terminal and having a node therebetween coupled by way of an output inductor to an output node from which said regulated DC output voltage is supplied;
• a control circuit for controlling switching of said at least one power switch of said output power switching stage for respectively different modes of operation of said multi-mode DC-DC converter in accordance with respectively different switching control signals applied thereto;
• and
• a plurality of switching control signal generators, which are operative to generate said respectively different switching control signals, in response to which said control circuit controls switching of said at least one power switch of said output power switching stage during said respectively different modes of operation of said multi-mode DC-DC converter, said method comprising the steps of:
• (a) monitoring an electrical parameter of one of said plurality of switching control signal generators;
• and
• (b) in the course of a transition between respectively different modes of operation of said converter, controlling the operation of said one of said plurality of switching control signal generators, in accordance with the electrical parameter monitored in step (a) so as to prevent an anomaly in said DC output voltage for said respectively different modes of operation of said converter.

A electronic system comprising:

• a functional circuit;
• and
• a multi-mode DC-DC converter for supplying a regulated DC output voltage to the functional circuit, the multi-mode DC-DC converter comprising:
• an output power switching stage having at least one power switch having a node coupled by way of an output inductor to an output node;
• a control circuit for controlling switching of said at least one power switch between different modes of operation of said multi-mode DC-DC converter in accordance with respectively different switching control signals applied thereto;
• a plurality of switching control signal generators to generate said respectively different switching control signals, in response to which said control circuit controls switching of said at least one power switch of said output power switching stage during said respectively different modes of operation of said multi-mode DC-DC converter;
• and
• a mode transition control circuit, coupled with said plurality of switching control signal generators, and being operative to prevent an anomaly in said DC output voltage at a transition between respectively different modes of operation of said multi-mode DC-DC converter.