Multiphase DC/DC converter with output phases deviated from or aligned with each other and driven with fixed on time
A multiphase DC/DC converter according to the present invention includes: a plurality of DC/DC converters whose outputs are connected in common to supply electric power to a load; a load state detection portion which detects a state of the load connected to the plurality of DC/DC converters and outputs a detection result; and a control circuit which drives each of the plurality of DC/DC converters based on outputs from the plurality of DC/DC converters, and based on an output from the load state detection portion, drives the plurality of DC/DC converters with output phases of the plurality of DC/DC converters deviated from each other or with the output phases of the plurality of DC/DC converters aligned with each other.
1. A multiphase DC/DC converter comprising:
a plurality of DC/DC converters whose outputs are connected in common to supply electric power to a load;
a load state detection portion which detects a state of the load connected to the plurality of DC/DC converters and outputs a load state detection signal;
a comparator which compares an output voltage generated by the plurality of DC/DC converters and a reference voltage with each other, and outputs a comparison signal;
a pulse signal generation portion which, based on the comparison signal, generates a pulse signal whose on time is fixed; and
a pulse distribution portion which, based on the load state detection signal from the load state detection portion, distributes successively a pulse of the pulse signal as a drive signal for the plurality of DC/DC converters so as to drive the plurality of DC/DC converters such that output phases of the plurality of DC/DC converters are deviated from each other or such that the output phases of the plurality of DC/DC converters are aligned with each other,
wherein an output stage of the pulse distribution portion includes:
a first logical-multiply operation circuit arranged to output a first logical-multiply operation signal of the load state detection signal and a second drive signal,
a second logical-multiply operation circuit arranged to output a second logical-multiply operation signal of the load state detection signal and a first drive signal,
a first logical-sum operation circuit arranged to output a first logical-sum operation signal of the first drive signal and the first logical-multiply operation signal to a first DC/DC convertor, and
a second logical-sum operation circuit arranged to output a second logical-sum operation signal of the second drive signal and the second logical-multiply operation signal to a second DC/DC convertor,
wherein the first and second drive signals are generated by successively distributing pulses of the pulse signal.
2. The multiphase DC/DC converter according to claim 1 , wherein the load state detection portion monitors an output current supplied to the load and aligns output phases of the DC/DC converter with each other when the output current increases.
3. The multiphase DC/DC converter according to claim 1 , wherein the load state detection portion monitors an output voltage supplied to the load and aligns output phases of the DC/DC converter with each other when the output voltage drops sharply.
4. The multiphase DC/DC converter according to claim 1 , wherein the load state detection portion aligns output phases of the DC/DC converter with each other and outputs the output phases when the load state detection portion detects a heavy-load state of the load.