METHOD AND APPARATUS FOR CALCULATING AN AVERAGE VALUE OF AN INACCESSIBLE CURRENT FROM AN ACESSIBLE CURRENT

摘要

In a power converter, a circuit determines an average value of an inaccessible current from an average value of an accessible current and a value of the operating duty cycle of the converter. A method of measuring an average value of an inaccessible current from a measured value of a current in a power converter by a duty cycle of a pulse width modulation (PWM) signal representing a duty cycle of the power converter. Coupling a voltage representing the measured value to an input of a low pass filter during a time period (D) and coupling the input of the low pass filter to a reference voltage during a time period (1−D).

主权项

1. A buck converter having a regulated output current comprising:
a current measuring device measuring an input current to the converter; a switch coupled to the current measuring device; a pulse width modulation (PWM) circuit coupled to receive an output voltage from the measuring device; an analog multiplier coupled to an output of the pulse width modulation (PWM) circuit to receive a signal (D) related to the duty cycle of the regulator and to a voltage representative of a predetermined value of output current from the converter.