Switching regulator with DC offset (bias) in controller
First Claim
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1. A switching power supply apparatus, including:
- a switching device for performing an on/off operation;
a control circuit for controlling on/off of the switching device;
a coil, a level of a current flowing therethrough being controlled by the switching device;
a capacitor that is connected to the coil and that performs rectification together with the coil; and
an oscillator for outputting to the control circuit an oscillating signal at intervals of a fixed time period for turning the switching device on,wherein the switching power supply apparatus outputs an output voltage from a node at which the capacitor and the coil are connected together,the switching power supply apparatus comprising;
a current detection portion for detecting a current value flowing through the coil, converting the detected current value into a voltage value, and then outputting the voltage value thus obtained as a current detection voltage;
a voltage source for adding an offset voltage to the current detection voltage from the current detection portion; and
a comparator for comparing the current detection voltage to which the offset voltage is added by the voltage source with a voltage commensurate with a difference between a voltage commensurate with the output voltage and a reference voltage,wherein, if the comparator finds a magnitude of the current detection voltage to which the offset voltage is added to be greater than the voltage commensurate with a difference between the voltage commensurate with the output voltage and the reference voltage, the oscillating signal from the oscillator is masked, and the switching device is turned off.
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Abstract
After a current value flowing through a coil L is detected, it is converted into a voltage value, is then inputted to an inverting input terminal of a comparator 4, and is then compared with a voltage indicating the difference between the value of a fed back output voltage and a reference voltage. A voltage source 20 is provided at the inverting input terminal of the comparator 4 so that an offset voltage is added to the voltage value to be inputted to the inverting input terminal of the comparator 4.
26 Citations
8 Claims
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1. A switching power supply apparatus, including:
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a switching device for performing an on/off operation; a control circuit for controlling on/off of the switching device; a coil, a level of a current flowing therethrough being controlled by the switching device; a capacitor that is connected to the coil and that performs rectification together with the coil; and an oscillator for outputting to the control circuit an oscillating signal at intervals of a fixed time period for turning the switching device on, wherein the switching power supply apparatus outputs an output voltage from a node at which the capacitor and the coil are connected together, the switching power supply apparatus comprising; a current detection portion for detecting a current value flowing through the coil, converting the detected current value into a voltage value, and then outputting the voltage value thus obtained as a current detection voltage; a voltage source for adding an offset voltage to the current detection voltage from the current detection portion; and a comparator for comparing the current detection voltage to which the offset voltage is added by the voltage source with a voltage commensurate with a difference between a voltage commensurate with the output voltage and a reference voltage, wherein, if the comparator finds a magnitude of the current detection voltage to which the offset voltage is added to be greater than the voltage commensurate with a difference between the voltage commensurate with the output voltage and the reference voltage, the oscillating signal from the oscillator is masked, and the switching device is turned off. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification