Step-up regulator with multiple power sources for the controller
View Patent ↗An output voltage VC obtained by boosting an input voltage VIN by means of a charge pump control circuit 3 of a charge pump 102 is supplied as a power supply voltage to a control circuit 4 of a step-up converter. It is thus possible to eliminate the need for a conventional self-bias method, eliminate switching from startup oscillation to main oscillation of the conventional self-bias method upon startup, and overcome problems caused by the switching of oscillation states, thereby achieving switching power supply circuitry starting in a reliable and stable manner.
1. Switching power supply circuitry, comprising:
a step-up converter for switching a DC input voltage by means of a switch element to obtain a DC output voltage boosted from the input voltage,
a step-up power supply for a control circuit, the step-up power supply for a control circuit for boosting the input voltage and outputting a second boosted voltage, and
a control circuit supplied with power at the second boosted voltage from the step-up power supply for a control circuit, the control circuit for controlling the switch element of the step-up converter when the second boosted voltage from the step-up power supply for a control circuit is equal to or higher than a predetermined operation start voltage, wherein only the output voltage of the step-up converter is supplied to a load.
2. The switching power supply circuitry according to claim 1 , wherein the step-up power supply for a control circuit comprises:
an oscillation circuit for generating driving pulses of a predetermined frequency,
a plurality of second switch elements for switching in response to the driving pulses, and
at least a single jumping capacitor charged/discharged by switching of the plurality of second switch elements.
3. The switching power supply circuitry according to claim 2 , wherein the oscillation circuit is a ring oscillation circuit including inverters of multiple stages connected like a ring.
4. The switching power supply circuitry according to claim 2 , wherein the step-up power supply for a control circuit comprises a stabilizing circuit for stabilizing the second boosted voltage.
5. The switching power supply circuitry according to claim 4 , wherein the stabilizing circuit is a series regulator.
6. The switching power supply circuitry according to claim 1 , wherein the control circuit comprises:
an error amplifier for comparing the output voltage of the step-up converter with a target value and generating an error signal and
a PWM circuit for generating a driving pulse for controlling a switching operation of the step-up converter in response to the error signal,
wherein when the output voltage of the step-up converter is equal to or higher than a predetermined value, at least one of the error amplifier and the PWM circuit is supplied with power from the output voltage of the step-up converter not from the second boosted voltage of the step-up power supply for a control circuit.
7. The switching power supply circuitry according to claim 1 , wherein when the output voltage of the step-up converter is equal to or higher than a predetermined value, the control circuit is supplied with power from the output voltage of the step-up converter not from the second boosted voltage of the step-up power supply for a control circuit.
8. The switching power supply circuitry according to claim 7 , wherein the step-up power supply for a control circuit is for stopping operation when the output voltage of the step-up converter is equal to or higher than the predetermined value.
9. The switching power supply circuitry according to claim 1 , further comprising:
a DC-DC converter for obtaining a second output voltage from the DC input voltage, and
a second control circuit supplied with power from the second boosted voltage of the step-up power supply for a control circuit, the second control circuit for controlling the DC-DC converter when the second boosted voltage of the step-up power supply for a control circuit reaches the predetermined operation start voltage.