Patent ID: 8907649
Filing Date: 2014-12-09
Classification: H02M,Y02B

Abstract:
1. A voltage converter, comprising: a voltage converting circuit that converts an input voltage into a low output voltage for a load; a pulse width modulation (PWM) controller, comprising: a comparator connected to the voltage converting circuit and outputting a PWM voltage to the voltage converting circuit; and a triangular-wave oscillator connected to a non-inverting terminal of the comparator, and outputting a sawtooth-wave voltage to the non-inverting terminal of the comparator; a feedback circuit connected to an inverting terminal of the comparator, and outputting a feedback voltage to the inverting terminal of the comparator; an adjusting circuit; and a measuring circuit comprising: a measuring resistor set between the voltage converting circuit and the load; and a power management unit connected to the measuring circuit; wherein the power management unit measures current flowing through the measuring resistor and controls the adjusting circuit to provide a pull-up voltage to the triangular-wave oscillator when the measured current decreases causing a duty ratio of the PWM voltage to increase; wherein the adjusting circuit comprises a first switch, a second switch and a pull-up voltage, the pull-up voltage is connected to the triangular-wave oscillator by the first switch, the second switch is set between the triangular-wave oscillator and ground; and wherein when the first switch is turned on, the second switch is turned off, and the pull-up voltage is applied to the triangular-wave oscillator.