Switching converter
To improve conversion efficiency at a DC-DC conversion time by providing driving units respectively for a plurality of switches and controlling the switches corresponding to a load current, an input voltage, an output voltage and an input/output voltage difference. When synchronously rectifying a plurality of first switches and a plurality of second switches by setting the first switches and the second switches alternately in an ON-state, the plurality of first switches are driven repeatedly in the ON- or OFF-state corresponding to a required output, the plurality of second switches are driven in the ON- or OFF-state in synchronization with the first switches, the driving of part of the plurality of first switches and part or all of the plurality of second switches is stopped corresponding to a load current value, an input voltage value, an output voltage value or an input/output voltage difference value.
1. A switching converter comprising:
an A-coil connected to an output terminal;
a first A-switch switching electric power outputted via the A-coil;
a second A-switch rectifying the electric power to become direct current thereby the second A-switch becomes set to an ON-state alternately with the first A-switch;
an A-driving unit driving the first A-switch and the second A-switch alternately;
a B-coil connected in series to the A-coil;
a first B-switch switching the electric power outputted via the B-coil and the A-coil;
a second B-switch rectifying the electric power to become direct current thereby the second B-switch becomes set to an ON-state alternately with the first B-switch;
a B-driving unit driving the first B-switch and the second B-switch alternately; and
a selection unit causing the A-driving unit and the B-driving unit to drive selectively,
wherein the A-driving unit is set to have a larger capacity than the B-driving unit, and the selection unit drives the A-driving unit when the output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value.
2. A switching converter according to claim 1 , wherein the first A-switch and the second A-switch is set to have a larger capacity than the first B-switch and the second B-switch have, and
the selection unit drives the A-driving unit when an output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value.
3. A switching converter according to claim 1 , wherein the A-coil may be set to have a larger capacity than the B-coil, and
the selection unit drives the A-driving unit when the output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value.
4. A switching converter according to claim 3 , wherein the A-coil has a lower inductance than the B-coil.
5. A switching converter according to claim 1 , wherein the A-coil extends from one terminal of the single coil up to a middle point thereof, and the B-coil extends from the middle point up to the other terminal thereof.
6. A switching converter according to claim 1 , wherein the selection unit receives information representing an operating state of a load-sided circuit, and drives the A-driving unit or the B-driving unit in accordance with the information.
7. A switching converter according to claim 1 , wherein the selection unit drives the A-driving unit or the B-driving unit in accordance with an output current.
8. An electronic device having a switching converter and a load operating by an output from the switching converter, the switching converter including:
an A-coil connected to an output terminal;
a first A-switch switching electric power outputted via the A-coil;
a second A-switch rectifying the electric power to become direct current thereby the second A-switch becomes set to an ON-state alternately with the first A-switch;
an A-driving unit driving the first A-switch and the second A-switch alternately;
a B-coil connected in series to the A-coil;
a first B-switch switching the electric power outputted via the B-coil and the A-coil;
a second B-switch rectifying the electric power to become direct current thereby the second B-switch becomes set to an ON-state alternately with the first B-switch;
a B-driving unit driving the first B-switch and the second B-switch alternately; and
a selection unit causing the A-driving unit and the B-driving unit to drive selectively,
wherein the A-driving unit is set to have a larger capacity than the B-driving unit, and the selection unit drives the A-driving unit when the output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value.