Patent ID: 9667142
Date: 2017-05-30
CPC Classifications: H02M

Claim:
1. A power supply device comprising: a plurality of switches; an inductor configured to charge and discharge electrical power in response to the plurality of switches; a first capacitor configured to generate a first output power supply voltage with electrical power discharged from the inductor; a second capacitor configured to generate a second output power supply voltage with electrical power discharged from the inductor; a switch control circuit configured to control the plurality of switches so that electrical power is charged into the inductor, discharged from the inductor, and distributed to the first and second capacitors in a time-division manner based on a switching cycle; a waveform generator circuit configured to generate a sawtooth wave having the same cycle as the switching cycle; a first circuit configured to output a first output voltage level in response to the first output power supply voltage and an associated first reference voltage; a second circuit configured to output a second output voltage level in response to the second output power supply voltage and an associated second reference voltage; a first control circuit configured to control an amount of electrical power to be charged into the inductor based on a first error output signal reflective of a difference between: (i) a sum of the first and second output voltage levels, and (ii) a first predetermined reference voltage; wherein the first control circuit includes: a first current detection circuit configured to detect a current flowing in the inductor and generate a voltage level proportional to the current flowing in the inductor; an addition circuit configured to generate a second voltage level by adding the first output voltage level to the second output voltage level; a second error detection circuit configured to detect the first error between the first predetermined reference voltage and the second voltage level and change the output level based on the detected amount of the first error; and a second comparator circuit configured to compare the output level of the second error detection circuit to the voltage level of the first current detection circuit and control the amount of electrical power to be charged into the inductor based on a result of the comparison; a second control circuit configured to control a distribution ratio at which electrical power discharged from the inductor is distributed to the first and second capacitors, based on a second output error signal reflective of a difference between: (i) the first output voltage level, and (ii) and second output voltage level; wherein the second control circuit includes: a first error detection circuit configured to change the output level thereof based on a ratio between the first output voltage level and the second output voltage level; and a first comparator circuit configured to compare the sawtooth wave to the output level of the first error detection circuit and control the distribution ratio based on a result of the comparison; wherein: one of the first and second output power supply voltages is a positive voltage and the other is a negative voltage; if the first and second output power supply voltages are both at their respective reference voltages, the first error detection circuit outputs a first voltage level; if the first output power supply voltage has fallen short of the first reference voltage or the second output power supply voltage has exceeded the second reference voltage, the first error detection circuit changes the first voltage level in a predetermined direction of polarity based on the amount of shortfall or excess; and if the first output power supply voltage has exceeded the first reference voltage or the second output power supply voltage has fallen short of the second reference voltage, the first error detection circuit changes the first voltage level in a direction of polarity opposite to the predetermined direction of polarity based on the amount of shortfall or excess.