DC/DC converter, control circuit thereof, and electronic apparatus

摘要

A control circuit of a step-up/step-down DC/DC converter includes: a hysteresis comparator configured to receive a feedback voltage and a reference voltage, compare the feedback voltage with a threshold voltage corresponding to the reference voltage, and generate a pulse signal indicating a result of the comparison; a logic unit configured to fix a second switching transistor at an OFF state and switch a first switching transistor based on the pulse signal in a step-down mode and fix the first switching transistor at an ON state and switch the second switching transistor based on the pulse signal in a step-up mode.

主权项

1. A control circuit of a step-up/step-down DC/DC converter, wherein the step-up/step-down DC/DC converter comprises:
an input line to which an input voltage is applied; an output line to which a load is connected; a first switching transistor connected between the input line and a first switching node; a first rectification element connected between the first switching node and a ground; an inductor connected between the first switching node and a second switching node; a second switching transistor connected between the second switching node and the ground; a second rectification element connected between the second switching node and the output line; and an output capacitor connected between the output line and the ground, the control circuit comprising: a hysteresis comparator configured to receive a feedback voltage corresponding to an output voltage generated in the output line at a first input terminal and a reference voltage at a second input terminal, compare the feedback voltage with a threshold voltage corresponding to the reference voltage, and generate a pulse signal indicating a result of the comparison; a logic unit configured to fix the second switching transistor at an OFF state and switch the first switching transistor based on the pulse signal in a step-down mode and fix the first switching transistor at an ON state and switch the second switching transistor based on the pulse signal in a step-up mode; a first buffer configured to generate a first ripple voltage having a first polarity which is synchronized with the pulse signal; a second buffer configured to generate a second ripple voltage having a second polarity which is synchronized with the pulse signal, the second polarity being opposite in phase to the first polarity; and a feedback circuit which includes a first feedback path and a second feedback path and is configured to superimpose the first ripple voltage on the feedback voltage via the first feedback path and superimpose the second ripple voltage on the reference voltage via the second feedback path in the step-down mode and superimpose the first ripple voltage on the feedback voltage via the second feedback path and superimpose the second ripple voltage on the reference voltage via the first feedback path in the step-up mode.