Switching power supply with mode transition control

摘要

A switching power supply that can suppress output variation at a time of transition of a control mode from a non-linear control mode to a linear control mode. The switching power supply includes instruction value forming circuitry that forms, in a linear control mode, a linear control instruction value for linearly control a switching circuit based on an error of an output voltage, and forms, in a non-linear control mode, a non-linear control instruction value for non-linearly control the switching circuit. The instruction value forming circuitry predicts, in the non-linear control mode, a linear control instruction value suited to the load current in the non-linear control mode, and uses the predicted linear control instruction value for an initial value of the linear control instruction value at a time of transition from the non-linear control mode to the linear control mode.

主权项

1. A switching power supply, comprising:
a DC-DC converter section for converting a DC voltage by a switching operation of a switching circuit; a current detection means for detecting a load current in the DC-DC converter section; and a digital control section for controlling the switching operation of the switching circuit, the digital control section including an error detection means for detecting an error in an output voltage of the DC-DC converter section, a control mode instruction means for instructing operation in a linear control mode when the error is substantially zero, and instructing operation in a non-linear control mode when the error is nonzero, an instruction value forming means for forming a linear control instruction value to linearly control the switching circuit based on the error in the linear control mode, and forming a non-linear control instruction value to non-linearly control the switching circuit in the non-linear control mode, the instruction value forming means predicting a linear control instruction value compatible with the load current in the non-linear control mode, and using the predicted linear control instruction value as an initial value of the linear control instruction value at a transition from the non-linear control mode to the linear control mode, and a pulse generation means for generating PWM control pulses based on the linear control instruction value and the non-linear control instruction value, to control the switching operation of the switching circuit.