US 2017/0322573 A1 · Voltage Regulators with Current Reduction Mode

Abstract

A voltage regulator provides an output current at an output voltage, based on an input voltage. The voltage regulator has a pass transistor for deriving the output current. The voltage regulator contains a drive transistor forming a current mirror in conjunction with the pass transistor, such that the output current through the pass transistor is dependent on a drive current through the drive transistor. The voltage regulator comprises an auxiliary transistor arranged such that at least a fraction of the drive current through the drive transistor flows through the auxiliary transistor. The voltage regulator has amplification circuitry to set the drive current through the drive transistor depending on the output voltage and on a reference voltage. The voltage regulator further contains control circuitry to detect an indication for a dropout situation where a difference between the input voltage and the output voltage falls below a dropout voltage.

Claims25

Dependent claims

1) A voltage regulator configured to provide an output current at an output voltage at an output node, based on an input voltage at an input node, wherein the voltage regulator comprises,

a pass transistor for deriving the output current at the output node from the input voltage at the input node;
a drive transistor forming a current minor in conjunction with the pass transistor, such that the output current through the pass transistor is dependent on a drive current through the drive transistor;
an auxiliary transistor arranged such that at least a fraction of the drive current through the drive transistor flows through the auxiliary transistor;
amplification circuitry configured to set the drive current through the drive transistor in dependence of the output voltage and in dependence of a reference voltage, if the voltage regulator is regulating the output voltage;
and
control circuitry configured to
detect an indication for a dropout situation where a difference between the input voltage and the output voltage falls below a dropout voltage of the voltage regulator;
and
in reaction to this, increase a resistance of the auxiliary transistor to reduce the fraction of the drive current flowing through the auxiliary transistor.

6 more elements

16) A method for operating a voltage regulator, wherein the voltage regulator comprises:

a pass transistor for deriving an output current at an output voltage from an input voltage, a drive transistor forming a current mirror in conjunction with the pass transistor, such that the output current through the pass transistor is dependent on a drive current through the drive transistor, an auxiliary transistor arranged such that at least a fraction of the drive current through the drive transistor flows through the auxiliary transistor, and amplification circuitry to set the drive current through the drive transistor in dependence of the output voltage and in dependence of a reference voltage, if the voltage regulator is regulating the output voltage;
wherein the method comprises
detecting an indication for a dropout situation where a difference between the input voltage and the output voltage falls below a dropout voltage of the voltage regulator;
and
in reaction to this, increasing a resistance of the auxiliary transistor to reduce the fraction of the drive current flowing through the auxiliary transistor.

2 more elements

Dependencies are inferred from the claim text.

Voltage Regulators with Current Reduction Mode

Life of this patent

Voltage Regulators with Current Reduction Mode

Life of this patent

Abstract

Claims25