US 5,969,513 A · Switched capacitor current source for use in switching regulators

Abstract

In voltage regulator with a power switch to alternately couple and decouple an input voltage source to an output terminal at a switching frequency, a current supply provides a current that is proportional to the input voltage, the capacitance of a ramp capacitor, and a switching frequency. To provide this current, a first capacitor is charged to a first voltage, the first capacitor is discharged to a second voltage through a variable current source at a rate which is controlled by a third voltage on a second capacitor, the first capacitor is connected to the second capacitor to bring the second capacitor to a fourth voltage to adjust the rate of flow of charge through the variable current source, and the first capacitor is recharged to the first voltage. The rate of flow of charge through the variable current source controls the supply of current to the application.

Claims18

Dependent claims

A voltage regulator having an input terminal to be coupled to an input voltage source at an input voltage and having an output terminal to be coupled to a load, comprising:

a power switch to alternately couple and decouple the input terminal to the output terminal with a switching frequency and a variable duty cycle;
a filter disposed between the input terminal and the output terminal to provide a substantially DC voltage at the output terminal;
a feedback circuit to measure an electrical characteristic of the voltage regulator and generate a control signal for maintaining the DC voltage at a substantially constant level;
a ramp voltage generator to generate a ramp voltage, the ramp voltage generator including a ramp capacitor having a capacitance;
a current supply coupled to the ramp voltage generator for controlling a current to the ramp capacitor, the current supply configured to cause the current flowing into the ramp voltage generator to be proportional to the input voltage, the capacitance of the ramp capacitor, and the switching frequency;
and
a comparator to compare the ramp voltage to the control signal and to generate an output signal to control the power switch.

4 more elements

Dependencies are inferred from the claim text.

Switched capacitor current source for use in switching regulators

Life of this patent

Switched capacitor current source for use in switching regulators

Life of this patent

Abstract

Claims18