Adjusting a current threshold of a power supply such that an output ripple voltage is within a set range

摘要

In an embodiment, a power-supply controller includes switching circuitry and an adjuster circuit. The switching circuitry is configured to cause a charging current to flow until the charging current has a predetermined relationship to a threshold, and to cause a discharging current to flow to an output node that carries an output voltage after the charging current. And the adjuster circuit is configured to adjust the threshold such that a ripple voltage superimposed on the output voltage has an approximately constant magnitude. For example, a power supply may include such a power-supply controller to maintain the magnitude of the output ripple voltage within a particular range during a pulse-frequency-modulation (PFM) mode despite variations in one or more parameters such as input voltage, output voltage, filter capacitance, phase inductance, and charging-current-sense impedance, from their respective nominal values.

主权项

1. A power-supply controller, comprising:
a comparator configured
to compare a charging current to a current threshold, andto detect that the charging current has a predetermined relationship to the current threshold; switching circuitry configured
to cause the charging current to flow, andto cause a discharging current to flow to an output node that carries an output voltage in response to the comparator detecting that the charging current has the predetermined relationship to the current threshold; and an adjuster circuit configured to adjust the current threshold such that a ripple voltage superimposed on the output voltage has an approximately constant magnitude.