Buck converter with reverse current detection and pseudo ripple generation

摘要

Provided is a DC/DC converter capable of immediately resuming to a normal operation from a state in which an output transistor is continued to be turned off when a reverse current is generated in a light load state. The DC/DC converter includes an ON-timer circuit including: a ripple generation circuit; a smoothing circuit; a timer circuit configured to output an ON-time signal; a logic circuit configured to detect a sign of generation of a reverse current; and a switch circuit configured to, based on a detection signal of the logic circuit, maintain an output voltage of the ripple generation circuit or control the output voltage of the ripple generation circuit to a predetermined voltage.

主权项

1. A DC/DC converter, comprising:
a comparator configured to output a signal indicating a result of comparison between a voltage obtained by adding a pseudo ripple component corresponding to an output voltage of the DC/DC converter and a voltage corresponding to the output voltage to each other, and a voltage obtained by adding the pseudo ripple component and a reference voltage to each other; an ON-timer circuit configured to input a control signal, which is synchronized with a signal input to a gate of an output transistor, and output an ON-time signal; a flip-flop circuit configured to input the ON-time signal of the ON-timer circuit and the output signal of the comparator; a drive circuit configured to input an output signal of the flip-flop circuit to control the output transistor; and a reverse current detection circuit configured to detect a sign that an output current flows reversely from an output terminal so as to output a detection signal to the drive circuit, the ON-timer circuit comprising:
a ripple generation circuit configured to generate and output a ripple component based on the control signal;an averaging circuit configured to output a voltage obtained by averaging the ripple component;a timer circuit configured to generate and output the ON-time signal based on the voltage output from the averaging circuit and the control signal;a logic circuit configured to input the control signal; anda switch circuit configured to input an output signal of the logic circuit to control an output voltage of the ripple generation circuit to be maintained when the sign that the output current flows reversely is detected, the switch circuit being connected between an output terminal of the ripple generation circuit and a ground terminal.